Catastrophe Theory
by AnotherSpoonyBard
Summary: In mathematics, catastrophe theory is part of the study of dynamical systems. In particular, it studies and classifies phenomena characterized by sudden shifts in behavior arising from small changes in circumstances. Or: in which the Winter War arrives at last.
1. Chapter One: Bad Moon Rising

_Disclaimer:_ I'm just going to say this for the entire fic: I don't own Bleach, its characters, storylines, or various licenses. I'm just some rando playing around in a rich guy's imaginary sandbox.

 _Notes:_ This fic is part of a larger AU. Some stuff will definitely not seem right if you haven't read the rest, but the short version is: Bleach minus Ichigo plus a consistent worldbuild. Also Karin, Yuzu and Uryū are shinigami. I swear it makes sense in context.

So... I'm actually thinking about upping the rating on this one. The violence will be mostly canon-typical, but... there will also be death. And things might get otherwise somewhat dark. I mean...Nnoitra and Szayelaporro exist, for one. If there's anything that I think seems especially potentially triggering, I'll warn on the specific chapter, but I have no way of knowing what will disturb other people—so please consider this a blanket content warning for violence, death, and creeps exhibiting extremely creepy behavior. Also language; Grimmjow and Kenpachi especially.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter One: Bad Moon Rising

* * *

I see the bad moon arising.  
I see trouble on the way.  
I see earthquakes and lightnin'.  
I see those bad times today.

I hear hurricanes a blowing.  
I know the end is coming soon.  
I fear rivers over flowing.  
I hear the voice of rage and ruin.

Hope you got your things together.  
Hope you are quite prepared to die.  
Looks like we're in for nasty weather.  
One eye is taken for an eye.

Don't come around tonight,  
Well it's bound to take your life,  
There's a bad moon on the rise.

-From 'Bad Moon Rising' by CCR

* * *

It smelled like rain.

The air was heavy with it—even the right clouds moved in, pushed forward by the kind of swift, whipping wind that preceded a massive storm. The same gusts picked her heavy hair up off her face and neck, tearing at it like a clumsy lover.

Yoruichi had little patience for those.

Tipping her head back, she contemplated the late evening sky, slowly turning the dark, oppressive grey of thunderheads. A loose fragment of plaster or something from the lot struck her in the cheek; the sting faded within half a second. Slowly, she uncoiled her senses, casting out over as much space as she could. Tessai's presence behind her in the shop was reassuring—but it was a certain conspicuous absence she felt most keenly.

"Man, I'm not really likin' this weather."

A shadow detached itself from the wall of the building next door; Yoruichi blinked slowly. Keeping her hands crossed over her chest, she shrugged.

"It rains a lot in this town."

"Yeah. We've noticed." Even over the rushing wind, the sound of his footsteps was distinct to her—he stopped a few feet away, facing in the opposite direction. When he turned his own eyes to the clouds, she supposed they must have made for a strange, mirrored image.

Knowing Shinji, it was probably on purpose.

"Anything yet?" she asked, pulling in a breath. It tasted like lightning.

"Not really. We'll keep patrollin' and all that. But you know what Aizen's like—it ain't gonna start until he wants it to."

The direction of the wind suddenly reversed; strands of hair swirled in her vision.

"Thanks," she said—she couldn't really bring any inflection to it, though. Her thoughts were too heavy just now.

"Eh. We owe you. Least we can do is keep an eye on things when that guy ain't around."

Yoruichi's grip on her arms tightened. "It will come to more than that," she warned.

She knew he knew that—but she didn't know how far he was willing to take this. Revealing themselves, possibly to the Gotei 13… that wasn't a move without risk. Not considering what they were, what they represented.

The sky flashed; still no rain fell. She hated this sense of _waiting_ for things to happen. By someone's else's design, no less. Yoruichi had stopped waiting for other people a long time ago.

Well, anyone but _him_ , anyway. But that was different.

"'Course it will," Shinji replied. "But we're not gonna do that part because we owe you." He paused; she heard the wry smile in his voice when he continued.

"We're gonna do that part for _us_."

* * *

There was something to be said, he thought, for thrones.

Of course, this was not the one he intended to sit eternally; but for now, it would do. The long table that accommodated his Espada stretched out in front of him; with but one more he would finally have the number he desired. For now, however, he would make do with these—there were pieces yet to be set in motion.

He was not so foolish as to believe that Kisuke Urahara's sudden disappearance into Hell meant he'd died. On the contrary—the longer that man spent there, the greater the chance that it would ultimately prove inconvenient. The solution, therefore, was rather obvious.

But of course, presenting a threat sufficient to lure the reclusive genius from his stint with the damned would require measures great enough to also draw the attention of Soul Society. Now that he was prepared for such, he could proceed as intended.

Sōsuke scanned the faces of those assembled; he would not send Gin or Kaname—they were better kept here, for the moment. After all, he wanted to provoke a response in stages. Let them thin themselves out by temperament, first. Such was the best move: he held the stronger cards, but their hand was—knowingly or not—stacked with the impossible.

He leaned his cheekbone onto his closed fist, the fingers of his other hand idly curling around the armrest of his throne. Once Baraggan's, of course—now significantly smaller. Sōsuke _did_ derive a certain sense of satisfaction from ripping apart perception. Particularly the perception of power. A subtle smile curled his lips.

"That's bad news for someone, ain't it?"

Sōsuke's eyes slid to his right. Gin wore the same facial expression he always did—the farcical rictus grin of inborn sociopathy. Unlike himself, his subordinate had never felt the need to hide that particular trait. It made the things he _did_ hide that much harder for the uninitiated to see. He'd even had Sōsuke fooled—even if not for nearly as long as he believed.

"On the contrary, Gin. I believe they will rather delight in this news."

He raised his voice only slightly to cut across the discussion below. "Ulquiorra. Yammy."

Everyone quieted immediately. They'd learned that much by this point, at least. The two Espada in question stood, fixing their attention upon him.

"I want you to take a… survey, for me." Sōsuke tapped his fist two fingers softly against the armrest of his throne. "Determine the number and power of the souls in the Jūreichi. If you encounter any resistance, eliminate it."

Ulquiorra bowed like the servile lapdog he was. Yammy abstained, but Sōsuke didn't mind. Gestures of obedience were empty—it was obedience itself that mattered. And _he_ was the one on the throne. For now, obedience was a foregone conclusion.

"Yes, Aizen-sama."

"Does this mean we're finally gonna start?"

Ulquiorra's dead eyes narrowed slightly, flicking to the left. Grimmjow, however, paid him no mind. That wasn't unusual. The question itself was fair, so Sōsuke answered.

"Yes, Grimmjow. It begins."

* * *

Yoruichi knew the moment the garganta opened across town. She'd been just about to sit down for dinner with Tessai, Jinta, and Ururu when it flared an angry red in her senses—a raw wound in the bounds of reality, almost. Someone was connecting two worlds, and the other one _wasn't_ Soul Society.

"Yoruichi." Tessai had sensed it too, of course.

She slapped her palms on her knees and stood. "Yeah." They had a better chance of making it there before anything bad happened than Shinji's people did. Gargantas were rare—it was seldom that even a Menos Grande acquired the ability to open one at will.

"Ururu, Jinta, go to the basement. Do not open the door for anyone but us," Tessai placed a hand on each of their backs and steered them out of the room. Jinta especially tended to be less likely to listen when Kisuke wasn't around; he seemed to understand the urgency of this situation, though, and grabbed Ururu's hand. They both disappeared behind the door to the basement stairwell, and Tessai pulled it closed, sealing it with kidō.

They exchanged a glance and a nod, then jumped into _shunpō_.

* * *

So this was the Jūreichi.

He supposed there was a decent amount of total spirit energy around—he'd heard that other parts of the living world were basically deserts by comparison. Still…

"Hey Ulquiorra! What about this one?"

Languidly, he moved his eyes to where Yammy was pointing, though truly he need not have bothered. It appeared as though one of the humans had barely survived the initial _gonzui_ —but she was nearly catatonic regardless.

"If you had bothered to engage your senses, you would know that she is trash."

A slightly stronger one was headed in their direction. Perhaps they had been sharp enough to sense the disturbance. Clearly not perceptive enough to notice that they were horrendously outmatched, however. A mistake that would doubtless be made apparent soon.

"How boring," Yammy said, oblivious to the change in their surroundings.

Ulquiorra did not bother to enlighten him.

"Bye then!" Drawing one foot back, Yammy made to end the human's worthless life in a single kick.

Ulquiorra was unsurprised when the heavy thud followed—without the snuffing of a life that Yammy was so clearly expecting. The impact was enough to kick up a cloud of grass and wet earth, but when it cleared, another human stood between Yammy and his would-be victim.

This one, Ulquiorra detected, had reiatsu that was not completely dissimilar to their own, if much, much weaker. He was large, for one of his kind, and darkly-complected.

"Huh? Who the hell are you?" Yammy, as usual, caught on slowly.

The human didn't respond, opening and closing his fist a few times. He had some variety of armor plating on it. To Ulquiorra's senses, it was vaguely similar to hierro—to withstand a blow from Yammy, it must have also possessed like properties. At least to a point.

"Ulquiorra!"

If he had been the type to sigh, he would have had to work to resist the urge. As it was, he simply blinked, hands still in his pockets. This would have proceeded much more quickly if Aizen-sama had simply sent him alone.

"No, Yammy. He is also trash."

"Okay then!" Yammy bent his knees and struck with an open palm.

The hit landed exactly on the human man's arm. Ulquiorra could hear the tendons rip and tear, along with the distinct wet snapping of breaking bone. Certainly a weak hierro, then. The human's skin tore open in several places, unable to withstand the reiatsu Yammy had infused into the hit. A fine red mist hissed from the wounds under the spiritual pressure, and the human crumpled to his knees.

That he was still conscious actually counted as impressive, for such a weak creature. Or perhaps Yammy was simply careless and failed to finish him with a single blow.

Ulquiorra's eyes narrowed—there were more incoming. But these… these were different.

"Yammy."

But the other Espada, unsurprisingly, was not listening. Instead, he drew back for another blow.

He was not nearly fast enough—nor were his senses good enough—to properly anticipate the intercession. Yammy's arm was met midair by someone else's; a dark hand wrapped around his much larger wrist, stopping it cold in the air.

"Tessai!"

The voice belonged to a woman—she matched a description Aizen-sama had given him. It would seem that they had drawn attention at last.

" _Bakudō #79: Kuyō Shibari_!"

The woman's companion surrounded Yammy with eight points of black energy. Before he could so much as react, a ninth appeared right over his chest—he was frozen in place.

Ulquiorra knew these: they were the cohorts of Kisuke Urahara. It was unfortunate that it was they who had made an appearance—engaging them would cause destruction on a scale Aizen-sama preferred to avoid at this particular point in time. Add to that…

His eyes slid to Yammy; he was still trying to free himself from the spell. Unfortunately, he was quite unable to do so, and the woman was making short work of him; a punch to the stomach and kick to the head like that probably would have dropped him to his knees if he could move.

She lunged to strike again—Ulquiorra knew he couldn't leave things any longer. Moving in front of Yammy, he caught the woman's foot in his hand. The sting against his hierro was only somewhat surprising. This was Yoruichi Shihōin, after all. Tightening his grip, Ulquiorra shoved her backwards with reiatsu, letting go in just enough time to send her flying. She landed without difficulty, but he had the time he needed.

Drawing his sword, he slashed through the black circle hovering over Yammy's chest, freeing him from the kidō and returning the blade to its scabbard in a single motion. The fool was fortunate that the other—Tessai Tsukabishi—was too busy healing the humans to join the engagement.

"Yammy. It is time to go." He summoned a garganta behind them, feeling the familiar essence of Hueco Mundo seep through the opening. He would never describe it as being like fresh air, but it was at least dense enough in reishi that it didn't feel so… _hollow_.

"Are you kidding? We've gotta finish this fight, Ulquiorra!"

Ulquiorra's expression didn't change—nor, for that matter, did his mood. All the same… there was no denying that Yammy at times was like a particularly slow child. "Don't be an idiot. That is Yoruichi Shihōin and Tessai Tsukabishi. At your current level, you would die trying."

The garganta yawned wider; Yammy grudgingly made for it. Ulquiorra permitted him to step inside first, not taking his eyes from the two former shinigami.

The woman was frowning deeply, her brows knit tightly. "So you're just running away?"

"Do not overestimate yourself, either," he told her tonelessly. "Do you think you would so easily defeat us, with those humans to protect?"

She must have seen the wisdom in letting them go, for she made no attempt to pursue. Behind Yammy, Ulquiorra stepped into the garganta, allowing it to close behind him. They had what they needed, anyway—Aizen-sama had asked for a reckoning of the spiritual energy present in the Jūreichi.

He would have it.

* * *

It was late afternoon when the captain returned to their office.

Rukia was still busy catching up on a backlog of paperwork—there were a lot of things that had gone undone or wrongly-assigned during the period where the Thirteenth had no vice-captain. Trying to get all of that sorted from what should be the third seats' and captain's duties was a bit of a stop-and-go process. She could probably just go ask Ise-san exactly what she was supposed to be doing and what she wasn't, but the Eighth was only _just_ giving the last of the Fifth's duties back to Hinamori—so they were pretty busy.

The door to the hallway slid open; Rukia glanced up, offering the captain a half-smile. "Ukitake-taichō. How was your appointment?"

He stepped into the captain's side of the divided room—the doors between the sections had remained open since they were unsealed two months ago. Rukia appreciated that; with so many new duties to get used to, she found herself with a lot of questions. It wasn't often someone went from unseated to second seat in one jump, after all. At least most other new vice-captains had experience as officers of some kind.

"Smoother than usual," he replied; his tone was pleasant as ever.

Really, if he weren't a generally honest person, she would have never been able to tell if he were being truthful or not—he wasn't really the type to let on when things were bad.

"Glad to hear it." Rukia turned back to his paper work, aware of him crossing the room to settle in at his own desk. The window to her left bathed the room in deep yellow light—the sun began to set over the Seireitei. Unfortunately, it would probably be a while yet before she'd done enough work to justify leaving for the day. Maybe she should think about sending down to the mess for something for both of them to eat…

Shaking her head slightly, Rukia went back to writing. For a while, the office was quiet except for the sound of brushes on parchment—with the occasional pause as Ukitake stopped to drink a mouthful of tea. She could feel the muscles in her back starting to get stiff; shifting, Rukia rolled her shoulders, rubbing the knot forming at the nape of her neck.

A soft ping caught her attention. Furrowing her brows, she raised her eyes, looking for the source of the noise. It chimed again; the captain started lifting stacks of paper and putting them aside, clearly in search of something.

"Sir…?"

"Ah, here it is." From a drawer in the desk, he removed a small, flattened circular object.

He set it down in front of him on the desk—Rukia blinked when a sheet of light projected upwards from it, forming into a flat, translucent screen. She could see shapes moving on the other side, like shadows, but it was impossible to make them out. At least until someone spoke.

"Ukitake-san."

Though the voice was tinny, Rukia recognized it immediately. Her eyes widened; her captain caught her eye over the projection and beckoned her forward with a gesture. Moving around to the same side as him, she peered over his shoulder at the front side of the screen.

Sure enough, there sat the image of Yoruichi Shihōin. Her entire right arm was covered in bandages. To her left was Tessai, looking solemn but unhurt.

"Hello, Yoruichi-san. I must admit, this is unexpected. I haven't heard from you in nearly six months now." Ukitake spoke with ease, like it was perfectly normal for exiles from the Soul Society to still be on communication basis with captains.

Then again… at this point, Rukia knew it _was_ —at least in a few cases.

Yoruichi's eyes moved momentarily from him to Rukia, but she didn't offer comment on the extra presence. "Yeah, well… up until now, there hasn't been much to talk about."

"Something's changed?" Ukitake's posture shifted; he drew himself up straighter in his seat.

She nodded. "Earlier today, two Arrancar came through a garganta into Karakura Town." On the screen, Yoruichi flexed her bandaged hand. "Tessai and I drove them off, but not before they'd killed nearly twenty humans. Only a couple of them in the area managed to survive."

"Arrancar?" Rukia asked aloud, shifting her eyes between Yoruichi and her captain.

Ukitake dipped his chin. "A Hollow that has torn off its mask and gained shinigami power," he said, dark brows knitting. "But I hadn't heard of the existence of any complete Arrancar—those Hollows who had come the closest in the past were unable to complete the transition."

Yoruichi shook her head slowly. "These two were complete. Aizen's doing, no doubt."

Ukitake frowned. "So you believe he is in Hueco Mundo, then?"

Rukia supposed that made sense, since he'd been whisked away by a garganta five years ago—but it was also a problem. Shinigami couldn't create the gates to that realm; there was no way to reach Hueco Mundo. At least… not that she knew of.

"Almost certainly." Yoruichi paused. "Ukitake-san. I need you to inform the rest of the Gotei 13 of what's going on. These Arrancar… they're much stronger than we anticipated. Even those of us who are here are going to need backup in case of more incursions. I don't know what he's planning—but my best guess is that we'll be seeing these guys again really soon."

"I understand," Ukitake said. "I'll get a message to the Sōtaichō right away; I don't know who he'll want to send in an advance guard, but there should be someone there within the next day or so."

Rukia pursed her lips; an uncomfortable feeling clenched in her stomach like a vise. "We were supposed to have another five years," she murmured. All the training that could have come between now and then… all the preparation. The feeling built towards her throat, threatening to choke her.

"I know," Yoruichi replied; her expression was stonier than Rukia had ever seen it. "But we don't."

* * *

"Go ahead, Ulquiorra. Show us what you saw and felt, in the living world."

"As you wish."

The Cuarta Espada reached up towards his own face. Without so much as a moment of hesitation, he gripped his own eyeball and tore it out with a wet squelch. Such a grisly ability, really; Sōsuke regarded the whole affair with a subdued amusement. Once Ulquiorra had crushed the organ in his fist, the reishi particles it comprised scattered.

The others present breathed deeply, pulling in the energy and the information contained within it. Of most interest to Sōsuke was the count and feel of the worthwhile reiatsu signatures in the area. Ulquiorra's pesquisa was the best of his fellows'. Consequently, the data were precise. He knew, therefore, that it was no accident or camouflage when he did not find the one he was looking for.

Sōsuke's smile faded, but he did not permit himself to frown.

"Heh. You weak little shits." Grimmjow quite obviously found fault with how his fellow Espada had handled the situation.

"What did you say?!" Yammy demanded.

From where he sat, back bowed and legs crossed, the other Espada smiled savagely. "I said: you're a weak little shit. Both of you. Can't even kill a couple of ex-shinigami—with direct orders, no less!"

"Please: do explain, Ulquiorra." Sōsuke already knew what the answer would be, but that wasn't the point.

With one eye and one empty socket where an eye had been, Ulquiorra fixed his attention on the throne, ignoring Grimmjow with customary precision. "We were given two objectives: the primary one was to gather information. The second was to eliminate resistance. Presented with a situation where performing a secondary function would interfere with the efficiency of the primary one, I chose not to."

"More like you ran away because you were fuckin' _scared_."

Yammy took a step towards Grimmjow; the latter was quickly in a crouch, all hint of lackadaisical posture gone.

"Enough." Ulquiorra barred Yammy from further escalation by physically retraining him—one hand just barely made contact with Yammy's elbow.

It was enough to halt the much larger Espada in his tracks. Really—they were more entertaining to watch even than the Gotei 13, at times. Sōsuke crossed one leg over the other, leaning his head on his hand.

"Apart from what your brothers might say," he said, quelling Grimmjow's rejoinder with a look, "I am rather impressed by your work, Ulquiorra."

His subordinate bowed immediately, crossing an arm in front of his waist and inclining himself with grace. "I am very grateful, Aizen-sama."

Sōsuke blinked slowly, pulling in a slow, relaxed breath. "Espada. Prepare yourselves and your Fracciónes for battle. It will not be long now." There were but a few more pieces to move into their places; then at long last, the board would be set for one final match.

He was looking forward to it.

* * *

Tōshirō stood stock-still at attention, drawing himself up as tall as possible. Of course, standing in between Kyōraku and Kurotsuchi made that a bit of a moot point; he did it anyway. Resisting the urge to cross his arms was harder, but he kept them at his sides like everyone else did. In the past, he'd spent this part of the meeting looking at the wall past Zaraki's elbow, but that side of the room was missing three people; it left him an unobstructed view of the other side of the chamber.

Sometimes, vice-captains would stand in for the missing captains, but this meeting had been called specifically only for the captains themselves. No one else was permitted to attend.

Yamamoto entered the hall from the door at the far end, striding past the assembled division leaders and planting himself at the head of the mismatched lines, as usual. At the heavy thud of his staff on the ground, all chatter ceased, and everyone's attention moved immediately towards him.

"The meeting will commence," he said sharply. There was a momentary pause. "There is grave news from the world of the living. Jūshirō, tell the others what you have heard."

An audible rustle filled the room as the people in it shifted to fix their eyes on the captain of the Thirteenth.

He didn't waste time.

"Complete Arrancar have been sighted in the world of the living. Two of them. There is good reason to believe that they are commanded by Sōsuke Aizen—and that he has discovered some way to awaken the Hōgyoku."

"Already?" Komamura asked. Since he didn't have the helmet on, it wasn't difficult to understand him for once.

Ukitake inclined his head. "Unfortunately so. There's no way of telling how long it has been awakened for, but it's likely that he's using it to create the complete Arrancar in the first place."

The room took this news in troubled silence; Tōshirō had to admit it was about as bad as news could get at this point. "How strong are these completed Arrancar?" he asked; he kept his expression impassive.

Ukitake grimaced. "At least one of the two that were sent to the living world is likely stronger than a Vasto Lorde."

"That's impossible," Komamura protested. "There's no way—"

"What's impossible about it?" Kurotsuchi asked the question snidely. "If a Vasto Lorde-class Hollow were transformed into an Arrancar, it would become stronger than it was before. So there is, by definition, the very possibility you deny."

Everyone took a few moments to digest that. Tōshirō thought it was all well and good to be matter-of-fact about it, but he wondered if anyone else had yet grasped the implications. _One_ Vasto Lorde was stronger than most of the people in this room. Not all of them, but most. If Aizen had managed to assemble even a few of them…

His fists clenched at his sides.

"We must send an advance guard to the Jūreichi," Yamamoto pronounced. "Given the apparent strength of the enemy, this group must contain two captains. Beyond that, at least two vice-captains with demonstrated talent for combat must go as well. Zaraki, Hitsugaya."

Tōshirō stiffened. "Sir."

"The two of you will lead the advance party. Take Matsumoto, Abarai, and at least one other officer of vice-captain level with you." There was only a beat of silence before he amended. "Other than Kusajishi."

"Yes sir."

"You are to rendezvous with Yoruichi Shihōin. You are not required to obey her orders, but I strongly advise you take advantage of what she already knows. I expect regular reports on the situation as it develops. The rest of you are to prepare your divisions for war."

With the echoing slam of wood on wood, the meeting adjourned.

* * *

Three heavy thuds on Karin's door woke her in the middle of the night.

"Hey, Kurosaki. Marching orders."

Karin rolled out of bed much faster than she usually managed in the morning, scrambling to open her door. Renji, already geared up, stood on the other side, arms folded into his sleeves. "We've got living world duty, if you're up for it."

"What?" She blinked at him, sleep-fogged brain still not quite caught up.

He rolled his eyes at her. "The Sōtaichō's ordered an advance team to the living world. No one else cared who the last member of the team was, so I said I'd pick. You wanna go or not?"

"But… why are we sending an advance team?" Logic caught up with her at that exact moment. "What happened over there?"

"Arrancar," he said, as though the single word should answer all her questions.

It didn't, but Karin figured there would be time for them on the way. Sliding the door shut in Renji's face, she threw open her closet and pulled down the first shihakushō she saw, throwing it on the futon and shucking her sleep shirt at the same time.

"Do I get a minute to tell Yuzu and Uryū, or what?" Shrugging partway into her shitagi, she remembered the likely state of her hair and half-flashed, half-tripped to her bathroom. Turning the light on and wincing when it nearly blinded her, Karin fumbled around in her drawers until her fingers found the familiar handle of her brush.

She could still hear Renji on the other side of the door, thankfully. "You can leave messages for 'em with the Jigokuchō, but this is a right now kind of thing," he said.

"Right; got it." Raking the brush through her hair a few times, Karin grimaced. Close enough. Throwing the whole thing up into a hasty tail, she hurried back to the futon; pulling on the rest of her uniform in the dark wasn't really that hard. Her hands knew what to do even if her eyes weren't any help.

She kept a small satchel of necessary supplies at the bottom of her closet, packed and ready to go. Grabbing it by the handles, she slung it over her shoulder and pulled the door back open.

"I'm good—let's go."

* * *

 _Term Dictionary_ :

 _Jūreichi_ – 重霊地 – "Important Spirit Ground." The place needed to forge an Ōken, along with 100,000 souls. In both canon and this AU, it's Karakura Town.

 _Gonzui_ – 魂吸 – "Soul Inhalation." An Arrancar technique whereby the practitioner inhales a large quantity of air, forcing the souls of nearby bodies to detach and be drawn into the mouth. Beings with reiryoku above that of an ordinary human may resist the technique, intentionally or not—as Tatsuki does in this chapter.

 _Hierro_ – 鋼皮 – The kanji are for "steel skin." The pronunciation given is (vaguely like) the Spanish word for "iron." Refers to the Arrancar's damage-resistant skin, the strength of which varies between them much like strength or speed do.

 _Kuyō Shibari_ – 九曜縛 – "Nine Sunlight Traps." Bakudō #79. Creates eight "black holes" which emit spiritual energy in the space surrounding the target; the ninth black hole manifests itself in the center of the target's chest. Meant to immobilize.

 _Pesquisa_ – 探査回路 – The kanji mean "probe circuit." The reading given corresponds to the Spanish word for "inquest." This is the measure of an Arrancar's ability to detect the location and power of reiatsu signatures, even at distance. Ulquiorra's is much better than Yammy's, obviously.

 _Fracción_ – 従属官 – The kanji are "subordinate officers." The Spanish is just for "fraction," which is either a poor choice when Kubo probably meant _faction_ , or else a pun on the fact that all of them have numbers. (Numbers "divided up" are fractions, har har.)

* * *

Anyway, there's chapter one of the Winter War fic. There's so many events to cover in this one that—unlike usual—I have literally no idea how many chapters there will be. If I had to take a wild guess, I'd say maybe 15-20? I'm cutting a lot for, well… format and manageable cast size, I guess. But I'm also going to be adding things, so eh. We'll see.

Pretty much anyone is open game for POV here, but if there's anyone in particular you want me to write as, I'm down for suggestions. Also happy to get critique re: characterizations. We don't get a _lot_ on most people, _especially_ the Arrancar/Espada and the Visored, so I do expect to have to extrapolate some. If you think I go off track, feedback would be appreciated.

Also, technically Ulquiorra is the "cuatro" Espada, while I have it written here as "cuarta." That's because cuatro just means "four" while cuarto/a means "fourth," and typing "four espada," even in a language I don't really know, would be physically painful. And to agree with 'espada,' which is a feminine noun, it should be 'cuarta,' not 'cuarto,' since I'm pretty sure it should change according to grammatical subject and not the gender of the person actually being referenced. (See: primera and sexa).


	2. Chapter Two: Trouble on the Way

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* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Two: Trouble on the Way

* * *

When the Senkaimon opened, it spat her out in her childhood.

The whole thing was pretty surreal—over time, her memories of her years in the living world had faded until she kept only the really basic stuff. Her family, a few pieces from school, some random information about how humans lived. But seeing it again right there brought those things to the front of her mind—a place they hadn't been in a long time. She saw a car and knew what it was, even if there weren't any such things in Soul Society and she'd forgotten about them before.

It had been the same way as when she came here to help Urahara; there hadn't been much time then, though. This was different—Renji said there was no way of knowing just how long they'd be here. War wasn't usually waged all at once; it happened in stages, with big gaps of waiting in between them.

"Kurosaki."

Hitsugaya's voice drew her attention. He was frowning at her, but that was nothing unusual. Karin realized belatedly that she had yet to jump from the gate's edge—he must have been waiting for her to go first or something.

"Hn." She pushed off the edge, launching herself out into open air. By this point, controlling her fall was child's play, and she landed softly next to Zaraki; Hitsugaya was right behind. Turning her eyes up, Karin watched the Senkaimon close, space gluing itself back together seamlessly.

Ground level was a neighborhood she recognized vaguely. Karin thought maybe it was somewhere between her dad's clinic—sold to someone else a long time ago—and what had been her elementary school. Easier than trying to remember where that was in relation to Urahara's place was just searching around for Yoruichi's reiatsu. Her weird gigai made it harder, but neither she nor that other guy Tessai were trying to conceal it.

"West," she said.

When they got there, Yoruichi and Tessai were waiting outside. The woman was leaning against the front of the shop, arms crossed over her chest. Tessai mirrored the body language, except he didn't lean. By the time they were within speaking distance, Yoruichi had pushed off from the wall and slid open the door behind her with a hand.

"They sent more of you than I thought," she said, glancing at each of them in turn. "Which one of you is in charge?"

"I am." Hitsugaya replied, taking a step forward. "Tōshirō Hitsugaya, captain of the Tenth."

Karin supposed that was probably for the best; there were only two captains here and the other one was _Zaraki_. He already looked bored.

Yoruichi appeared unsurprised. "Yoruichi Shihōin. This is Tessai Tsukabishi." She paused to allow Tessai to nod, then continued. "We can house you here, but it's going to be close quarters."

"That's fine."

It wasn't like they had anywhere else to go.

Yoruichi nodded shortly and turned, leading them all into the shop. The front room was unchanged; various sorts of candy made for colorful shelves—surprisingly tidy for a guy like Urahara. Probably one of the others did it. Everything was clean, but not especially well-used. They passed through to the back quickly, and Yoruichi ushered them all into a larger living room. Zaraki took up a spot against the wall, leaning his head back and closing his visible eye. Karin wouldn't be surprised if he'd decided to take a nap.

The rest of them squeezed in around a circular table. Tessai left with a nod at Yoruichi, who sighed.

"What else can you tell us about the situation?" Hitsugaya asked.

She shook her head. "Not a lot. I can share my guesses, but this isn't exactly my area." Yoruichi met Karin's eyes for a moment.

Karin understood.

"Any chance we can get a message to Urahara, or anything?" she asked.

"Believe me, I've been trying. He left behind a bunch of notes: on Hell, on Arrancar, on Aizen, even—but the parts I understand only tell me so much. I'll give you what I know, and what I guess, and you can decide what to do with it."

Karin huffed out a breath, falling back onto her rear and pulling her legs under her. Seiza was way too uncomfortable to maintain for long. "Lay it on us, I guess."

Hitsugaya shot her a vaguely-disapproving look; she shrugged at him. Yoruichi observed the byplay without comment, though her mouth did turn up at one corner.

"Sure." She took a deep breath only to sigh it right back out again. "Kisuke's notes indicate that an Arrancar can be made of any Menos-class Hollow. They're never complete naturally; but they can self-stabilize in an incomplete form. The Hōgyoku can make complete Arrancar, with full access to both their shinigami and Hollow powers. The ones we encountered even had zanpakutō; I'm assuming Aizen stole them at some point."

Karin had never heard of anything like that; but the other three at the table didn't seem surprised at all, so probably they had.

"Anyway, it seems like they can take various forms; of the two we fought, one was probably an Adjuchas. The other… I suspect the other was once a Vasto Lorde. I don't know how they measure up against anything else Aizen has, but if he was willing to send them out…"

"Then they probably aren't his closest underlings," Hitsugaya finished. Lifting his arms, he folded them over his chest. His eyes fell shut; a furrow appeared between his brows.

"Well, we know he's got Tōsen and Ichimaru," Renji said, shifting slightly awkwardly and glancing at Rangiku. "Maybe these are the next two guys down the ladder?"

"That's optimistic," Yoruichi said. "Think about it: this is Aizen. He's not the type to just throw his aces out at the start of the game."

Karin scowled. She hated the idea that he thought of it that way—like a game. She'd seen some of the damage the bastard had done just by betraying people, never mind this. But she guessed someone like that probably _didn't_ care enough about anyone to think of it any other way.

"He would have used exactly what he needed to in order to accomplish his goal," Hitsugaya added. Opening his eyes again, he fixed them on Yoruichi. "Any idea what that was?"

She pursed her lips. "They weren't here very long. And they didn't seem very interested in fighting Tessai and I when we showed up. If I had to guess, I'd say they were more of a scout party than a vanguard. It's what I'd want to do—get the lay of the land first."

"So we're probably expecting more then?" Karin asked.

Yoruichi's reply was cut short by Tessai's return. He bore a tray laden with tea and snacks; no sooner had he placed it down than Karin and Renji dug in. She hadn't had breakfast, and the slight time-displacement in the dangai was always weird on her system. Rangiku waited until they'd cleared away before taking her own.

Hitsugaya abstained entirely. "If this first attempt was merely to gather information, then yes. I suspect we are."

* * *

"This is fuckin' ridiculous." Grimmjow stalked restlessly from one end of the room to the other. His Fracción watched him pace; Shawlong stood, one shoulder leaned into the doorjamb, hands in his pockets. The others sat either on the floor or the sofa, waiting.

They were waiting for him to tell them what to do. Sometimes he hated that about them; the way they hardly ever bothered giving their own damn opinions—the way they just _followed_. Gave up. Cowards.

When pacing was no longer enough to get rid of his restless energy, he started to grind his teeth. The muscles in his jaw jumped; the mask fragment on one side _itched_ something awful. He flexed his fingers in his pockets sharply enough to crack the joints; a breath hissed out from between his teeth. All this damn _quiet_ set him on edge in a way battle never did—he could feel it more keenly then. The roiling mass of souls that made him up. They didn't have any individuality anymore. They were just food. Fuel. But sometimes he swore he felt them clawing at his head, trying to get _out._

"I can't believe that damn prick. There were enemies right in front of him, and what the fuck does he do? He runs away like a goddamn dog with his tail between his legs! And Aizen doesn't even do a damn thing!"

What was the point? Why let an enemy go when the opportunity to fight them was there? Didn't trying to hold all the power in drive him _crazy_? Grimmjow's nostrils flared. Self-preservation, maybe. Even _he_ had those instincts. It was the reason he was here in the first place.

But his self-preservation instincts weren't nearly as strong as the rest of them. Yanking one of his hands from his pockets, Grimmjow dragged it down his face, fingers crooked so that his nails scraped over his hierro. Two of them hooked over the mask fragment—he pulled uselessly at it.

"We're going," he declared.

It was the only way he'd ever work out this restlessness. The only way he'd ever be himself.

Shawlong bowed slightly. The others stood at once. Not one of them argued with him. If they'd just agreed, that was fine… but even if they disagreed, they'd never say.

He hated it.

Shoving his hand back in his pocket, Grimmjow led the way from their quarters. Las Noches was stupidly-big, but all they really needed was a spot empty enough to call a garganta. The nearest one wasn't far away.

"You sure you want to do that?"

The lackadaisical voice could only belong to one person.

Grimmjow paused midstep, whipping his head sideways. Starrk's eyes were always dull like that—as if nothing ever interested him. It didn't make any damn sense to him, but at least the Primera wasn't a little shit like Ulquiorra.

"Why? Got a problem?" His eyes narrowed.

Starrk shrugged. "I don't really care what you do, but Aizen's not going to like it."

"He'll change his tune when I bring him shinigami heads on a pike." Grimmjow felt a familiar electric ripple over the surface of his skin at the thought of it. The restlessness began to subside.

"I don't think he will," the other Espada said evenly.

"You ordering me not to go?"

"Tch." Starrk uncrossed his arms and let them drop lazily to his sides. "Even if I did, it wouldn't make a difference, would it?"

It was a question that didn't really need answering.

Starrk sighed. "Be careful out there, Grimmjow. You shouldn't underestimate the shinigami." He blinked once and turned away, down a different hallway. Probably to find somewhere to sleep or something.

 _Careful_ wasn't in Grimmjow's makeup. Not by a long shot. Starting forward again, he turned into an empty room. It would do.

Time to prove once and for all that he was stronger than that damn Cuarta.

* * *

Well. Yoruichi hadn't been lying when she'd said space was going to be tight.

What was formerly one room had been divided into two with a screen, and the two parts together had to fit the five of them. Apparently Urahara's room was better not lived in—which was probably fair. Rangiku had only ever really learned about him in a secondhand way, but he _was_ the man who'd thought the Twelfth Division was a good idea. There were probably all kinds of… _things_ , in there.

She certainly had no intention of finding out.

The floorspace in the room was just enough for the necessary futons—all the rest of the furniture had been moved. Rangiku couldn't help but chuckle at the brief twitch in her captain's eye. She herself had grown up with considerably less space, so it wasn't really a big deal to her. Actually, it might be nice to fall asleep to someone else's breathing again.

Plus, she could have so much fun teasing everyone else.

"Karin-chan! You're sleeping in my half. It'll be great." She latched herself on to the much shorter woman's arm, suppressing her laughter at the flat look she got in return.

"Yeah… I'm sure it'll be a real slumber party," Karin drawled.

Rangiku blinked. "Slumber party?" She'd never heard of such a thing.

"Uh… never mind. Living world thing."

"People do this voluntarily?" Tōshirō asked, eyeing Zaraki suspiciously.

He _did_ seem like the kind of guy who would take up a lot of space. Renji was pretty tall too, actually. Rangiku bit the inside of her lip, trying to keep a straight face.

" _Some_ people," Karin corrected. "And… not quite like this. But it doesn't matter." Freeing herself from Rangiku's hold, she tossed her satchel onto one of the futons on the smaller side.

"Might be best if we got some shut-eye now, actually."

Renji had a point: they hadn't exactly slept the night before. Rangiku was used to late hours, but admittedly even she was a bit tired.

Karin frowned. "Shouldn't we do that in shifts? In case something happens?"

"No need," Rangiku said, digging around in her pocket. She produced a denreishinki, handing it to Isshin's daughter. "Renji probably forgot to get them to issue you one, but the rest of us have these. They'll make a lot of noise if there's a Hollow in the area. It should work for Arrancar, too, right?"

Tōshirō nodded. "Yes. But Kurosaki has a point; it makes sense for at least one of us to always be awake."

Karin blinked; Rangiku could read her confusion and the reason behind it as clearly as if she'd actually said the words. She probably expected Tōshirō to ignore her most of the time—to be fair, it _was_ what he usually did. But this was a mission; and her captain took those seriously enough to put aside the worst of his cold shoulder tendencies.

"Uh… guys?" Renji sounded unusually hesitant. "Where's Zaraki-taichō?"

"What are you talking about, Renji? He's right…" Rangiku trailed off. Wait. Where _was_ he? He'd been standing right there not moments ago—she could have sworn it.

"Uh…" Karin started.

She was interrupted by a shrill ringing sound from the denreishinki in her hand—and from the other two in the room. Her eyes rounded in surprise; she flipped open the screen. Rangiku leaned down to look over her shoulder. The radar showed several red dots at the same location, but within seconds they were separating from one another and spreading out.

There were six of them.

* * *

Kenpachi figured that maybe the meeting part of the deal was required, but he didn't really have the patience to sit around for the stuff afterwards. Not that he had anything against any of the people they'd brought—he wanted to fight Renji at some point soon, actually. And that girl—Karin or whatever—she had matches with Ikkaku sometimes. He liked the way she handled those.

But he wasn't here to talk strategy. All of that crap tended to fall apart the second he was in a real fight anyway. The only strategy Kenpachi bothered to use was 'hit it, and if that doesn't work, hit it harder.'

Considering how many fights he'd won, he figured it was a pretty good strategy.

 _Finding_ a fight was a little harder than he thought it'd be, though. The noisy thing in his hand was pointing him one way, but the bastards kept moving around, forcing him to change directions. It was worse than just doing what Yachiru told him—at least she didn't change her mind so damn often.

Which one of these assholes was the strongest, anyway? The den-whatever didn't tell him. It'd be really fuckin' annoying if he spent all this time running around and found some weak Hollow or something. Maybe his head start was enough that he'd be able to get close enough to figure it out before the others got there.

Maybe he'd get to take all of them at once before the others got there.

A grin stretched over his face. Now _that_ was his idea of a good plan.

One of the red dots on the screen changed directions again; it looked like it was coming in his direction. That was good—if it was brave enough to come to him, maybe it would be strong enough to bother with.

Snapping the mechanical thing shut, he shoved it between the layers of his shihakushō and grabbed the hilt of his nameless, sheathless sword. Drawing it free, she raised it to block the incoming attack he'd barely registered, his body moving on instinct alone.

It met far more resistance than he'd been expecting, colliding with a kick aimed for his head. That was good—that was very good.

The Hollow who'd aimed it sprang away, landing casually on the ground. He had on some weird kinda white clothes and looked mostly like a human, but there was a pretty big hole right under his lungs. That and the piece of mask on his face made Kenpachi figure he was probably one of those Arrancar. Maybe he was _really_ lucky and it was that Vasto Lorde one Yoruichi had been talking about.

That'd make Kenpachi's fuckin' _day_.

The Arrancar kept his hands in his pockets. Past the mask part, Kenpachi could see that he was smiling widely—pretty much the same expression he had, actually.

"Hey you," Kenpachi said. "You're an Arrancar, right?"

"And from that outfit, you're a shinigami," the other guy said.

He sprang forward, covering the space between the two of them quickly. Whipping his body around, he went in for Kenpachi's head with a kick. It had some stupid name to do with a building or something—Kenpachi didn't care what shit was called.

That time, he decided to let it hit, just to see what he was looking at here. It caught him square in the temple, snapping his head to the side. For a moment, the vision in his uncovered eye actually whited out.

This was _great_.

Swinging for where the Arrancar landed in retaliation, Kenpachi felt his smile stretch wider. His sword went through nothing but empty air. The heavy whistle stopped when he drew it back—his opponent still hadn't taken his hands out of his pockets, much less drawn his sword.

"Kenpachi Zaraki, Captain of the Eleventh Division," he said by way of introduction. He thought it was only polite to let a decent fighter know who was gonna kill him, after all.

"Captain?" The blue-haired guy grinned savagely. "Excellent. I'm Grimmjow Jaegerjaques, Sexta Espada."

Kenpachi had no idea what the fuck an Espada was—but since it didn't really matter to him, that was fine. Shifting his grip on the hilt of his sword, he tightened his fingers around it. "Are you the strongest guy here?"

"That's me," Grimmjow replied. "How about you?"

"Damn straight I am."

"Then I guess both of us are having a lucky day, Kenpachi Zaraki."

Kenpachi couldn't agree more.

* * *

Tōshirō could tell from the fluctuations in Zaraki's reiatsu that he'd found and engaged at least one of the Arrancar—a glance down at his denreishinki informed him that one of them had stopped moving completely. That left five in motion. He didn't really like the idea of taking on more than the number of people on his team, but at least Shihōin was with them. One-on-one matches with Hollows this strong wasn't the wisest thing, either, but they had little choice.

It seemed to be the strategy the Arrancar were employing as well—where they'd started to split, now they converged again. Their course was obvious; they were going to meet Tōshirō's party head-on.

All five of them appeared at once. Shihōin reacted the fastest, springing into the air and kicking one of them off his course, away from the rest. With a jaunty salute, she followed, flashing away with the speed he'd expect of someone once given an epithet for the technique.

The ones that remained landed about ten feet from his group. The one front and center had a strange Hollow mask that capped his head and protruded out to his right. The largest had a bright red mohawk, And the other two were a rotund Arrancar with a mask that still covered half his face and a thinner blond one.

It was difficult to differentiate their reiatsu when they were all standing that close together—they all had a similar feel for some reason. But he was pretty sure the one in the middle was the strongest.

"Hey Hitsugaya. I'll take the big guy." Kurosaki pointed at the one with the red hair.

The Arrancar in question folded his arms and smirked. "I guess you're eager to die, little girl."

She clenched her jaw. "Maybe. Wanna find out?" Kicking off the ground, Kurosaki angled herself away in the air, leaving plenty of room for everyone else to fight.

The Arrancar followed.

Renji glanced at Tōshirō and shrugged. "Any preference?"

Considering he had no idea what abilities any of them had, he simply planned to deal with the strongest. "The leader."

"All right. Blondie, you're with me."

Apparently the Arrancar were amenable to splitting up in any fashion, because those two moved away as well. Considering that, there was only one thing to conclude.

"There's no specificity to your targeting. You're just here to kill anyone who gets in your way."

The man in front inclined slightly. "Just so," he said mildly. "As from your manner of dress I assume you're in charge here, I suppose you will be wanting to fight me, yes?"

Tōshirō reached back for Hyōrinmaru's tsuka.

"How observant of you."

* * *

What the heck was _with_ this guy? It was like her sword couldn't cut him.

Hisaku's sealed blade clanged off skin as hard as metal; Karin flashed away before he could punch her in retaliation. Considering that was the third time something basically the same had happened, she figured there was no need to mess around any longer.

" _Sobiero, Hisaku!_ "

Drawing her blade in a swift motion, Karin lunged, aiming for the Arrancar's shoulder. The fire released with her shikai hit him first—the blade itself was a second later. Still, he resisted it; Hisaku left a cut in him this time, edges blackened, but it was shallower than it should have been.

He glanced down at it, as if surprised that she'd managed to make him bleed. He opened his mouth—probably to say something—but Karin honestly wasn't interested in hearing it.

" _Sakebe._ "

A dull roar filled her ears, competing with the sound of her heart. Hisaku lit on fire; Karin channeled her reiatsu into the blade, focusing on sharpening it to as fine a point as possible. It was a lot like that time in Hell. Except… if she killed this guy, he wouldn't just pop back up a couple hours later.

She swallowed, then shot forward.

The strike she aimed for the Arrancar never connected; he stepped aside to avoid it, then brought both fists down together. The blow caught her right in the back; it was only a second later that she crashed facefirst into the roof of the building below.

She heard a wet crunch at the same time as she felt a terrible pain in her face. It took a moment, but the blood seeping out of her mangled nose told her she'd definitely broken it.

"Shit." She could taste it on her tongue, too.

Karin pushed herself to her feet—she'd definitely be mostly purple tomorrow morning from all the bruises she'd just earned. But she was damn lucky nothing else had broken, or she'd have worse problems right now than being forced to breathe out of her mouth. Her legs protested when she used _shunpō_ to avoid the follow-up and get back in the air; she had no choice but to suck it up and deal.

She couldn't let herself get hit like that again if she wanted to live. Which meant she had to move too fast for him to catch her.

" _Tobase._ "

Sucking in a breath, she relished in the feeling of lightness the technique produced for only a second. Wary of getting in too close, she flung fire arcs from Hisaku's blade instead, keeping herself in constant motion so she wouldn't make an easy target. The fire wasn't doing a _lot_ of damage, but it did some. Enough that parts of the Arrancar's skin were reddening and blistering, anyway.

But she could already feel herself tiring and slowing down; that damn limiter was a pain in the ass. Rangiku had put in the request to get them released on their way over—but if this guy got her even once more, she might not make it that long.

"You call this fire?" the Arrancar taunted. "I can barely feel it."

Karin bit her tongue against the automatic instinct to taunt back. The more bored he was right now, the better. The last thing she needed was for him to get serious while she still had the limiter on.

"Come on," she muttered to herself, throwing three more lashes from different angles.

He just stood there and tanked all of them. She grimaced; she was splitting her reiatsu too many different ways. Letting the _Tobase_ technique go out, she pulled the flames at her feet back to her sword, pumping more reiatsu into the fire there. It flared, the red color of it brightening to scarlet.

"This is pathetic," the Arrancar said. "Get out of my way so I can kill your friends."

At the words, he reached to his sash, laying a hand on the hilt of his sword. " _Okiro, Volcánica_."

When she'd heard that Arrancar had zanpakutō, she'd figured that meant they'd work in a basically similar way. Karin was not expecting that at the end of the process, her opponent would look a lot more like a Hollow. He was pretty big—an Adjuchas, most likely. His arms were huge for his body, and they had what looked like vents or something cut into them. Smoke curled out of the gaps, thick enough that she was glad she wasn't that close.

Oh great. This was gonna be a pain.

* * *

"What the hell is that?"

One minute, he'd been fighting a humanoid Arrancar.

Now, he was staring down a giant… Hollow? But he still also kind of looked like a human? Renji wasn't sure what to make of it, but he wasn't liking the massive reiatsu spike that came along with the transformation. That was not great news for him.

"This? This is how we Arrancar release our zanpakutō, brother." Yylfordt—Renji was fairly sure that was his name—tilted his head.

It was pretty obvious that those horns were the main way he attacked in a form like that. Renji lowered his stance, holding Zabimaru in a one-handed grip directly in front of him. His other hand, he kept free for now.

"Oh yeah? Is that so?" He spoke more to buy time than because he was curious—but the information would be good if he could get it.

How much longer was it gonna take to get the damn seals undone?

"It's called," Yylfordt paused, bracing himself on the ground. "Resurrección!"

He charged. Renji had expected that much. What he hadn't expected was just how _fast_ he'd be. Unable to dodge, he raised Zabimaru to block; a dull clang sounded out when he successfully staved off one of the incoming horns.

The other broke skin between his neck and shoulder. Renji strained to push back; the effort shook his arms. Even without momentum, Yylfordt's strength was enough to keep pushing forward—centimeter by centimeter, the horn dug in to Renji's muscle. Gritting his teeth, he adjusted his feet and stepped out wide, breaking the deadlock and sending Yylfordt pitching forward. He recovered too quickly for Renji to press the advantage, and the horn left a broad slash on his strong side.

Yylfordt charged again; this time Renji was a little more prepared. He was slower than the Arrancar with his limiter on, so he had to make sure he didn't need to move far. Timing his motion, he just barely got out of the way of the charge—one of the horns sliced through part of his shihakushō. The second the dangerous part was past him, he retaliated, lashing out with Zabimaru's greater range. The segmented blade struck the back of Yylfordt's neck, where he'd aimed, but bounced off; it left only a shallow cut behind.

Apparently, _all_ the Arrancar's abilities had gone through the roof when he released his zanpakutō.

"Renji!" Matsumoto's voice reached him over the noise of nearby battles. "Authorization came in!"

As if to prove her right, the camellia below his left collarbone disappeared when he struck it. The reiryoku it had kept sealed flooded back into his system all at once; he pushed out a heavy, relieved breath. Much better.

"Looks like we can stop messing around," he muttered, mostly to himself. Yylfordt charged again—avoiding it was much easier this time.

Renji really wasn't in any kind of mood to be prolonging the fight—that was for spars and friendly matches, not this kind of situation. With the energy he'd just gained, he should be able to get it over with. Should be a good opportunity to field test something new, too. He half-smiled at Yylfordt, eyes narrowed to slits.

"Sōō Zabimaru. Bankai."

* * *

 _Term Dictionary_ :

 _Volcánica_ – 火山獣 – The kanji read "volcanic beast." The pronunciation is the word "volcanic" in Spanish. Eduardo's resurrección. The release command is _okiro_ (起きろ), which in context is "blaze up" or surge in the fire-specific sense. Since we're talking about a volcano, "erupt" is the best match in English. Eduardo can control fire/heat via his fists when it's released.

 _Resurrección_ – 帰刃 – The kanji are "returning sword," while the Spanish is "resurrection." I'm treating this _slightly_ differently from canon; an Arrancar can _only_ seal their powers in a zanpakutō, and it works a lot like a shinigami's pattern of release. Unlike most shinigami releases, however, a resurrección usually alters the Arrancar's physiology more than their weapon. More on that… eventually.


	3. Chapter Three: Earthquakes and Lightning

_._

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Three: Earthquakes and Lightning

* * *

"You're not too smart, are you?"

Yoruichi smirked at her Arrancar opponent. He'd refused to give his name—not that she'd asked for it. Really it suited her just fine. A couple good hits had convinced him that he needed to use that zanpakutō of his. The issue for him was that it just made him larger, and the root _problem_ was that she could hit him too easily in the first place.

Really, between this guy and the other one, there was no contest. It was actually kind of insulting—that Aizen knew she was here and had sent a guy like this to try and slow her down. Actually… she'd have to think about that later. The move didn't make sense to her, and Aizen was for all his faults a very effective strategist.

Flexing her bandaged hand, she lifted her other one to the shoulder. Tessai had worked on it, but that other Arrancar's skin had done a number on her, for sure. And her left leg, too—she'd have to avoid using both in this fight, and _shunko_ was right out.

Fortunately, she wasn't going to need any of it.

"What was that, shinigami?" The armor plates on his segmented body made a grinding rasp of a sound when he moved. He had several rows of short legs, like a centipede, and held the first third or so of his body aloft.

His back third whipped forward, crashing to the ground where she'd stood not a moment before. Yoruichi shifted her weight, springing away on her right leg. She landed lightly several feet back. It would have been better if she'd exited her gigai before coming here—but she'd been in it so long that doing that suddenly wasn't a smart idea.

In front of the mouth of his Hollow mask, he started to collect light green energy. Recognizing a _cero_ when she saw one, Yoruichi _tsk_ ed.

"If you're going to try something like that, I guess I have to kill you faster." So much for taking her time assessing what these Arrancar were capable of. The town couldn't afford the damage something like that would do.

The Arrancar shot his _cero_. Channeling reiatsu into her left arm, Yoruichi sprang forward, catching the light in her fist before it could spread. With a grunt, she strained forward; slowly closing her fingers over the blast. The resistance gave out; her fist snapped shut, smoke coiling from the sides.

If she'd been able to see more than his eyes under the mask anymore, she'd wager he'd be pretty surprised—which was a good thing. The longer he spent gaping at what had just happened, the more time she had to finish him off. Gathering her legs under her, she jumped, carrying herself up to the level of his head. Her right knee slammed into the underside of his jaw, snapping his head back. Yoruichi pivoted in midair, springing sideways and taking hold of either side of his head with a hand.

With a sharp jerk, she wrenched. The exoskeleton protecting his neck cracked and shattered—the spine inside was weak by comparison. A cascade of wet crunches reached her ears; she let go and landed on his opposite side.

The Arrancar, its neck broken, teetered in midair for several long seconds, then fell sideways, dissolving into reishi particles before he could even hit the concrete street.

* * *

Even knowing, intellectually, that the Arrancar were at least as powerful as Adjuchas-class Hollows hadn't quite prepared Tōshirō for having to fight them with a limiter on. Though he had enough power to use bankai at this level, it wasn't anywhere near the usual power of Daiguren Hyōrinmaru. That—combined with this… resurrección the Arrancars could use—had backed him into a corner.

Matsumoto had been hit by a lucky blow from the large one; he could still sense her reiatsu, but she wasn't doing well. That had left him with no option but to fight them both—if he left her opponent to just finish her off, he'd never forgive himself.

His breath sawed in and out of his lungs, whistling softly past his teeth. He had one advantage—this Shawlong was a talker, and very confident in his ability to win at any time he chose. Since he was also the leader, the other one didn't attack without his permission, either.

A glasslike tinkling sound gave away that another of the petals at his back had crumbled away. The process was slower than it used to be—the five years of preparation had helped in that respect at least. But… Tōshirō's hands tightened on Hyōinmaru's tsuka. Even that meant nothing until the limit release authorization came through.

Shawlong lunged, sharp digits outstretched. Tōshirō flashed aside—but one of the claws caught him across the stomach, biting deep into his skin. Blood welled to the surface of the wound; it was just one in a dozen similar gashes he's received since the start of the fight. Grimacing, he directed more reiatsu into his bankai, ice crawling over his abdomen and freezing his blood where it was.

It was nothing but a temporary fix, but at least it meant he wouldn't bleed out.

Gritting his teeth, Tōshirō retaliated, surging forward and swinging his zanpakutō for Shawlong's center mass. The Arrancar evaded—he thought he'd heard the other one call it _sonído._

The other one.

Tōshirō whirled in just enough time to catch the incoming fist on his sword, stepping away before it could become a lock. His opponents pursued, crashing right through the ice wall he put up to try and stop them. Even his flight speed wasn't enough to—

" _Unare, Haineko._ "

A cloud of grey ash swallowed the second Arrancar; within the next moment, he was in pieces on the ground.

"Renji!" Matsumoto shouted to the distantly-visible Abarai. "Authorization came in!"

That would explain the sudden power differential. Tōshirō lifted one of his hands, striking the spot on his chest where the daffodil was. His reiatsu flooded back in like sudden high tide; he felt like himself again.

Shawlong must have been perceptive enough to understand the difference; his single visible eye went wide. "Retreat!" he called, presumably to whatever allies he had left.

Tōshirō hiked an eyebrow. "Were you under the impression we were just going to let you run?" he asked levelly.

At his command, ice bloomed on the Arrancar's shoulder, spreading rapidly until he was completely encased in it. Tōshirō closed his fist; the ice splintered and cracked. With a crash it shattered, breaking the Arrancar apart with it.

* * *

Renji raised the snake skull in front of him, crossing it over his other arm in a two handed block. His bent knees absorbed the full impact of Yylfordt's charge—one of the horns on the Arrancar's head broke apart from the force of the impact. The other made a nasty screeching noise as it slid off the gauntlet.

"How is this possible?" The Arrancar leaped back. "You're just a—"

Renji rolled his eyes. "Spare me."

Just a. He'd been _just a_ his whole damn life. Just a kid, just a stray dog, just a part of the common rabble. Just a sixth seat. Just a fukutaichō.

Fuck. That.

"I'm Renji Abarai, vice-captain of the Sixth Division." He'd earned as much, dammit.

He didn't use the blade in his gauntlet. It was still a little moody at times—besides that, he wouldn't need it for this. Yylfordt charged again, this time ducking in low and actively trying to avoid a block. That was fine. Renji was pretty tired of being on defense anyway.

Drawing his right arm back, he timed his punch to connect with the middle of Yylfordt's brow. The cracking sound it made split his ears; for a moment, he wondered if he hadn't accidentally broken Zabimaru.

But the snake skull gauntlet was fine—the only thing that had busted was Yylfordt's head. The mask fell off in chunks, each of them turning into reishi and dissolving. Slowly, the rest of the Arrancar's body did the same.

Renji dismissed Zabimaru with a thought; the zanpakutō clicked decisively as he slid it back into the sheath.

"…Just the guy who killed you."

* * *

Fortunately, Karin was still alive when she heard Rangiku tell Renji the limiters could come off. She wasn't a vice-captain, but they'd stuck one on her anyway, because apparently her reiatsu was close enough. She'd thought it was kind of cool, at the time—to be treated the same way as the others. She'd felt a secret bubble of pride in her chest to be acknowledged that way.

Fighting this guy kind of made her wish they'd overlooked her, just this once.

The sound of her hand slapping the skin just under her neck was wet—she was bleeding in some places and crispy in others. The smell of her burnt hair—more of a taste, considering the mangled state of her nose—pretty much made her want to hurl, but she swallowed down the bile. Her power was coming back, and it was one hell of a rush.

"That's more like it," she grumbled.

Of course, she was still burnt and bloody, and he was still big and tough—but Karin had dealt with big and tough plenty of times before. Big wasn't important, and tough only mattered if there was an 'er' on the end. Cracking her neck to the side and trying not to wince when it pulled at an angry group of blisters, she figured it was time to find out who had that 'er.'

Already, Hisaku's flames were brighter; the heat that rose off of them warped the air in front of her like an afternoon in the desert. Karin tightened her free hand, feeling warm liquid drip from her fingers. The blood loss was making her feel lightheaded, which definitely didn't help her nausea any. Stronger or not, she had to finish this quick, or she'd pass out right there.

Flames burst to life at her feet as she activated _Tobase_ ; speed was the order of the day. The Arrancar drew back one of his heavy fists, charging his hand with heat. That was the form of it—pure heat. Damn hard to see coming. Good thing the vents were easy to spot.

Sucking a breath through her teeth, she held it. Throwing herself forward into _shunpō_ , she shoved her reiatsu into her sword, turning herself so that she was almost horizontal in the air, tucking her feet up close to her. It would minimize the chance of getting hit by the vent on his shoulder, the only thing that could throw her off-track once she'd avoided his hand.

She flew true—all she had to do was cut once, and she'd have his head. The moment she felt her blade hit flesh, Karin squeezed her eyes shut. The follow-through was blind, but her body knew what to do. Hours of training—with Renji, with Ikkaku, with Uryū—had made sure of that.

Skin and bone ended. Air began. Karin opened her eyes again for the landing, touching ground softly and sheathing her zanpakutō. She turned in just enough time to be splashed with hot, heavy blood—the Arrancar's head passed over her in the air before bursting apart into white light.

It was in her hair, on her face. Sticky, warm—too warm, too alive still. Pressing her hand to her mouth, Karin fought back her gag reflex. She could feel it everywhere—it slithered down her skin even in the places she was sure it hadn't touched. Her blood, his blood, she didn't damn well know. She tried to pull in air, thick with smoke and the smell of death—

She flashed to the nearest hedge and lost her tea and snacks in the bushes.

* * *

Kenpachi couldn't remember the last time he'd had his back to a wall in a fight like this.

Oh wait. He could. It had just been a _really_ fuckin' long time ago.

He'd done away with the limiter a few minutes ago. Probably permission had come through since he even could. But even if not, screw that stupid rule; this Grimmjow guy was clearly a threat, and Kenpachi wanted to get him to use more of his power. In order to do that, he actually had to use more power _himself._ That was a kicker—it sure as hell didn't happen often.

The familiar hum of battle surged through his body, like metal struck so hard it vibrated. There was always that chance of _snapping_ , of breaking apart and dying; everything was best that way.

Grimmjow had really tough skin—so far Kenpachi hadn't been able to do more than cut the surface of it. Slowly letting out his power, making the hum higher and louder in his bones, he struck again; only to be blocked again. The Arrancar caught his blade on his crossed arms—at least he'd finally taken 'em out of his pockets.

"Come on," Grimmjow said, pushing back against where they were locked. "Show me your bankai. That's what you shinigami are all about, right?"

"Bankai?" Kenpachi echoed. "I ain't got one of those stupid things."

Grimmjow's mouth pulled to the side. He kicked off from the ground and aimed his knee for Kenpachi's chin. Leaning backwards, he avoided it; the bells on the ends of his hair jangled at the sudden move. He slashed from left to right—but Grimmjow wasn't there any more.

He appeared right behind, his heel hitting Kenpachi's shoulder. He felt one of the bones there crunch—how long had it been since he'd broken anything? He might be able to go all out with this guy. But he had to make sure.

"No bankai? Aren't you the strongest in your group? What kinda bullshit are you givin' me here, Kenpachi Zaraki?"

Kenpachi bared his teeth in a broad grin. "No bullshit. I don't need any of that fancy shit to win my fights. All I need is what I've already got. That's what Kenpachi means—the strongest in Soul Society."

Grimmjow landed in front of him, back in position for another head-on clash. Kenpachi liked that.

"All of Soul Society, huh? Now there's somethin' I gotta see." The Arrancar cracked the knuckles of his left hand with his right, then switched. "Why don't ya show me why they gave you that name?"

Kenpachi slung his sword casually over one shoulder. "Nobody gave me any damn thing," he replied. "I took it." He reached up, laying his fingers on his eyepatch. With the limiter gone, this was the next step if he was gonna push this battle to the edge. He had no idea what was going to happen—but that was the best part.

Before he could yank the damn thing off, they were interrupted by a screeching noise. Over Grimmjow's shoulder, he could see a black line, one that spread out into some sorta gate or something—it looked kinda like teeth. Kenpachi hoped there were more Arrancar in it.

But from the way Grimmjow's face went from grinning to looking like he wanted to spit, Kenpachi figured it was probably something annoying.

And then out stepped that fuckin' bastard Tōsen. Kenpachi had never liked him. Always preachin' about what other people should do, about how fighting was wrong or whatever. There was some big fancy word for it that Yumichika had used. Sanct—sancti-something. Kenpachi usually didn't bother with words that were too fancy, but he kinda wished he'd remembered that one, just so he could use it now.

"Grimmjow." Tōsen talked with the exact same 'I'm better than you' voice he used on Kenpachi.

Fuck. He was gonna ruin everything, wasn't he?

Unless Kenpachi killed him first.

He lunged—Tōsen drew his zanpakutō and blocked in one motion.

"You here to fight me, too?" Taking both of them at once would be fun, maybe.

"No," Tōsen replied flatly.

A burst of reiatsu forced Kenpachi to take a step backwards. Grimmjow was scowling openly. Kenpachi didn't know if he was just as pissed to have the fight interrupted or what.

"Grimmjow, you are to return to Hueco Mundo immediately. Aizen-sama is furious at your insubordination. Your punishment will be decided shortly."

"Like hell you're leaving," Kenpachi said. "I was just starting to have fun!" He let his reiatsu go, pressing down with all the pressure the eyepatch would let him have.

Tōsen calmly parried his next attack; Kenpachi didn't let up. Grimmjow stepped into the gate with a sour face, shaking his head. Tōsen flashed into it as well; it closed on them even though Kenpachi tried to rip it open again with his zanpakutō.

It wasn't like he needed another reason to hate Tōsen.

But he damn well had one now.

* * *

Tōshirō leaned back against the wall. The little girl—Ururu—had taken his haori away for laundering, which he supposed it really needed. He'd swapped into his spare shihakushō when Tsukabishi was finished with the healing kidō. His hair was wet from the bath he'd taken to wash all the blood off; everyone had agreed to let Kurosaki go first on that one, though. She'd been both the worst injured and the messiest. When one of the other people in contention was Zaraki, that said something.

He pushed a breath out of his nose, letting his eyes fall shut. Tōshirō could still sense Abarai and Zaraki in Tsukabishi's room. It was the closest thing they had to the Fourth—but the former Grand Kidō Chief had readily admitted that kaidō was not his area. He'd done pretty damn well for the amount of injuries they'd brought back with them, but Tōshirō knew the slash across his stomach was going to scar.

He wondered how many new scars the others had picked up today.

He also wondered if he should have made some decision differently. Would this have gone better if he'd picked the last member of the team himself? Or if he'd insisted that the fight be a five-on-five melee?

No. They'd just have gotten in each other's way. They were strong individual combatants, but they weren't a team; not even close. He and Matsumoto could fight together—he guessed Abarai and Kurosaki could have, too. Would two-on-two have been better?

Tōshirō scrubbed a hand down his face. He was supposed to be a captain. He was supposed to be a _genius_ —even if he hated the word, it was supposed to be _true_. Basic, fundamental answers like this should not have eluded him. They wouldn't have eluded Kurosaki-taichō.

His mouth twisted into a scowl.

He hated it when he started to think like that.

He felt Matsumoto's reiatsu before she entered. Straightening his posture, Tōshirō blanked his expression, opening his eyes and forcing his scowl to resemble something neutral. He wasn't too good at that. By now, he let his reputation for grumpiness do some of the work for him, though. His vice-captain was the only one who tended to nag him about it.

Well, and Momo—but not as much lately.

"Wow, it's raining pretty hard out there, huh?" His vice-captain's eyes went to the window to his left.

Tōshirō grunted noncommittally in reply. Matsumoto regarded him steadily. He wasn't too fond of that look on her—it meant she was figuring something out. Usually something he didn't really want her to know.

He was surprised when her next words had nothing to do with it. "Hey, have you seen Karin-chan, taichō?"

He scrunched his eyebrows at her. Obviously she wasn't in here; he cast around with his spiritual sense. "She's on the roof," he said flatly. "Which you could have easily figured out for yourself."

Matsumoto pursed her lips. "Mm," she replied.

He didn't know what she meant by it.

"Should she really be out in this weather, though?"

Tōshirō stared blankly at her. "Kurosaki's an adult, Matsumoto. As long as she stays where we can sense her and obeys orders on the battlefield, she can do whatever she wants."

Matsumoto tilted her head to the side. Her hair was damp—it left a dark spot on the shoulder she'd braided it over. "You know… Karin-chan hasn't been on that many missions to the living world. Just patrols, and the occasional Hollow." She sighed quietly. "I'll bet that Arrancar was the first time she killed something without a mask."

Tōshirō stiffened. The implications of _that_ were clear enough. "You think she's taking it badly?"

His fukutaichō smiled. There was no happiness in it—not even humor. "Is there any other way to take it?"

He pushed out a breath, crossing his arms over his chest. Clearly, Matsumoto wanted him to go talk to her. Some childish part of him wanted to insist that she or Abarai handle it. Both of them were closer to Kurosaki than he was. And if Matsumoto had ever been bothered by her existence the way he was, she'd apparently gotten over it.

But neither of them was the commanding officer in this situation. Tōshirō knew from experience on the other side of it that he had to be the one to do this. Well, him or Zaraki—and the latter was a terrible idea for a lot of reasons.

"Fine."

* * *

It didn't take him long to find her. She was sitting on the roof: legs drawn up to her chest, chin propped between her knees, staring at nothing. At least she'd put up an _enkōsen_ over her head.

He was kept from wondering if she knew he was there when she turned her eyes on him. Just long enough to confirm that he'd been noticed; she turned back again afterwards. He resisted the instinct to scowl.

She still looked like her father.

"Kurosaki."

She tipped her head to one side, leaning a cheek against a knee to cock an ear in his direction; no acknowledgement beyond that. Grimly, he moved to a better distance for talking, clearing the water from part of the roof with a hand gesture. Putting another shield kidō above his own head, he sat down about a foot from her, facing the same direction.

"I'm not gonna screw anything up," she said after a moment. "So you don't have to bother with making sure I'm okay for the mission or whatever. I am."

 _I'm fine, Shiba-taichō. It's not like it's a big deal. They were traitors anyway._

The sound of rain hitting an _enkōsen_ was similar to the soft patter it made hitting glass. Tōshirō had always felt comfortable during storms—even the thunder and lightning hadn't bothered him, as a child. They relaxed him, the same way other people enjoyed being out in the sun. Not that he ever let himself indulge in the feeling with subordinates around, of course.

"I know," he said. "You'll be fine."

Kurosaki's face contorted—she was clearly not expecting him to say that. Rapidly, she smoothed it over, hunching her shoulders and wrapping her arms around her legs. He thought maybe she was suspicious of what he'd said—perhaps she thought he didn't mean it. That offended him for a second… but then he wondered if maybe it wasn't the logical reaction.

 _I hate it when everyone treats me like a kid. I earned my spot here—you said so yourself!_

"What you're thinking right now… it doesn't mean you don't deserve your position."

From the corner of his eye, he saw her fingers tighten on her leg. Her visible skin was too pink—he didn't think it was residual burns, either. Her knuckles went white.

"Yeah? And how do _you_ know what I'm thinking?"

He shrugged. "You're not the first person who's ever thought it."

Tōshirō half-expected her to assert her uniqueness or something—to say that everyone was different. A true thing, but not one that mattered all the time. But she didn't. Instead, she pursed her lips—thoughtfully, if he was reading the expression right. Matsumoto was much better at this kind of thing than he was.

"I've been trying to decide if it's better or worse that I didn't know his name," she admitted.

He shook his head. "There's no right answer to that." At least, he'd never found one. He was pretty sure her father hadn't, either—not if their version of this conversation was anything to go by.

"Yeah, probably not." She blew out a breath in a gust. After a significant pause: "Does it… get easier?"

His frown deepened. "Define 'easier.' You stop hesitating—if you don't, you die. Most people stop counting." Or just… lost count, which wasn't quite the same.

"Am I gonna be able to sleep without seeing it again?"

"Eventually."

Lightning forked across the sky—the roll of thunder wasn't far behind. He felt it in the tiles of the roof, a subtle vibration he knew to feel for.

She nodded slowly. "I guess that better be good enough, huh?"

 _I'm stuck with the rest of it forever, aren't I?_

"Yeah."

* * *

Renji didn't ask why Urahara had a giant screen that could connect to Soul Society.

Some things just didn't need explaining.

At least it made reporting in easier. Though the fact that the Sōtaichō looked twice his normal size was pretty unnecessary.

"Abarai-fukutaichō. Report."

Automatically, Renji straightened, folding his hands behind his back. One good thing about having to report to Kuchiki-taichō all the time was that he knew how it was _supposed_ to be done.

"Sir. The Jūreichi was invaded by a party of six Arrancar about two hours after our arrival." He didn't really want to think about how that would have gone if they hadn't been around. Yoruichi and Tessai were strong, no doubt about it, but if they were the only people here, and _six_ Arrancar had shown up…

"Casualties?"

"Only injuries on our side, sir. Kurosaki suffered the worst of it. Hitsugaya-taichō and Zaraki-taichō both required considerable treatment as well. Matsumoto-fukutaichō had a concussion, but all of the injuries have been treated pretty well."

Yamamoto folded his hands at the top of his staff, peering at Renji from under heavy brows. "And the enemy?"

"Five of the six were killed, sir. The remaining Arrancar was returned to Hueco Mundo by ex-captain Tōsen."

It was hard to tell with the facial hair, but Renji was pretty sure the Sōtaichō scowled at the name. "Have you gathered any further intelligence from these encounters?"

Renji nodded. "Yes sir. We've learned more about the powers of the Arrancar, and we have a theory about their internal organization." Or at least, they'd scraped one together from the more talkative Arrancar and what Zaraki had remembered about his opponent.

"Explain."

Renji resisted the urge to shift his weight. "There are at least two different numbering systems for the Arrancar. The first one is just order of… birth. It starts at eleven. The ones we fought were definitely among the first of them, but that doesn't seem to have any direct connection to their power." He paused for Yamamoto's slight nod, then continued. "The numbers one through ten are apparently different. We think those _are_ ranked by power. One of the Arrancar that invaded this time was number six. He called himself an Espada, so we think that might be what the top ten go by."

The Sōtaichō didn't move, but Renji swore his brows got heavier-looking.

"And this Espada… how strong was he?"

Renji gritted his teeth for a second. "He seemed to be fighting evenly with Zaraki-taichō, sir, but it's hard to say."

Zaraki hadn't let himself go all the way, but… from the way he described it, neither had the Espada. He hadn't said it, but it was clear enough to Renji that he hadn't been sure exactly how much his opponent was holding in reserve. If someone like that was only number six…

"And their powers?"

"They have zanpakutō; it's pretty clear what Aizen did with the asauchi that went missing. The Arrancar can release them, like we can, but from what everyone said, it changes their physical form rather than what ours do. Some of them get other abilities to go with—those vary a lot like shinigami zanpakutō abilities. The group of them we fought had mainly physical abilities, but Kurosaki fought a fire-user. They can also use _cero_."

Yamamoto was really hard to get a read on; it didn't help that Renji had spoken to him _maybe_ twice before this—and not really directly, either. He didn't seem the type to let on if he was worried about something, anyway.

"Anything else?"

"At least one of them used something a lot like _shunpō_. They call it _sonído_. And like before, they're harder to cut or burn than they look. That's all we were able to figure out."

"I see. What do you believe the power level of the others is? The ones who are not Espada?"

Renji grimaced. "If they're all about the same as these ones, then we're probably looking at class seven. Most of them could handle anything up to a vice captain easily." It was definitely good that they'd brought only people who were at least the fukutaichō-level, because the jump between the average seated officer and the average second seat was like night and day.

"Do you believe your current personnel are adequate to this task, Abarai-fukutaichō?"

He kept his sigh quiet. "That really depends on what they send, sir. For stuff like this: yeah, we'll get by. If they sent six of those Espada instead?" He shook his head. "Hitsugaya-taichō asked me to put in a request for backup from the Fourth. We're okay for now, but if the injuries keep piling on like this, we probably won't be able to keep up."

"Hm." The Sōtaichō blinked at him. "I will consider your request. For the time being, remain in communication with Soul Society regularly. Unless there is another engagement, I will expect a report from at least one of you each week. Report immediately if there are further incursions. Do you understand?"

Renji bowed. "Yes, sir."

"Good. You are dismissed."

The screen flickered, then went black. Renji heaved out a heavy breath. Well… time to go tell the others.

* * *

 _Term Dictionary_ :

 _Hyōrinmaru_ – 氷輪丸 – "Ice Ring." Tōshirō's zanpakutō. The release command is _sōten ni zase_ (霜天に坐せ), "sit upon the frozen heavens." The primary method of attack with Hyōinmaru is the creation and manipulation of ice. His bankai is _Daiguren Hyōrinmaru_ (大紅蓮 氷輪丸), "Grand Crimson Lotus Ice Ring."

 _Sonído_ – 響転 – The kanji are "Sound Ceremony" while the Spanish just means "sound." The Arrancar's answer to _shunpō_ or _hirenkyaku._

 _Haineko_ – 灰猫 – "Ash Cat." Rangiku's zanpakutō. The release command is _unare_ (唸れ), "growl." Similar in principle to Byakuya's Senbonzakura, the blade of the sword dissolves, in Haineko's case into ash. She can use the hilt to direct the ash to cut anything it touches—the power varies according to mow much of the ash is used.


	4. Chapter Four: Bad Times Today

.

* * *

Catastrophe Theory

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Four: Bad Times Today

* * *

"Welcome home, Grimmjow."

Aizen was really a smug bastard. It set his teeth on edge—then again, what didn't? Grimmjow was a damn raw nerve, and he knew it. He couldn't settle from that fight earlier, either; that had made going to the living world completely worth it. He'd been building to it, to that thrill that would finally click all his jagged pieces into place and smooth him out. But it hadn't happened before Tōsen got there and dragged him away, the self-righteous prick.

Grimmjow was gonna kill him someday. And he was gonna _enjoy_ it.

It hadn't escaped him that he returned alone. His fracción were dead. Every last one of them—except the parts that were still in him. It only added to his restlessness. He'd grown used to them trailing behind him. Useless baggage. Even more annoying when they weren't there anymore.

The last thing he wanted to fucking deal with right now was the snake on that throne.

"Well?" Tōsen prompted. "Is there anything you have to say for yourself?"

What? Was he expecting him to get down on his knees and beg for forgiveness? Not fucking likely. Grimmjow might serve—now, because he had to—but he didn't _snivel_. He wasn't a coward.

His lip curled. "Not a damn thing."

Tōsen's hand tightened on his zanpakutō. "You bastard—"

Electricity prickled on Grimmjow's skin; the muscles in his back shifted and jumped under his flesh. His body, his instinct, yowled at him to fight. If he couldn't fight that shinigami, anyone would do. But self-preservation reared its head, and he ground his teeth instead.

"It's all right, Kaname." Aizen on his throne was the picture of calm. A fake sun, hung in a fake sky.

Even lesser stars could burn, though.

"I'm not upset. Not at all. I feel that Grimmjow's actions were indicative of a rare loyalty and desire to serve."

Every word. Every word smothered him. Saddled him with things he didn't feel. Things that were the opposite of his nature. Chains around his arms. His legs. And one that never left his neck. The threat of what would happen if he didn't obey. Didn't let himself be talked about like that. Like a servant.

Like he was insignificant.

Aizen knew. There was no way he didn't know. No way this was anything but intentional. He was looking down on him, and not just because of the stupid throne. Grimmjow seethed, just as much as Tōsen was seething next to him. Neither of them could show it in front of Aizen. It was the only thing they had in common.

"Yeah," he said. "That's right."

It only took an eyeblink for Tōsen to grab his collar. Grimmjow's insides were screaming for a fight. For something to do battle against. Death wasn't the point. Destruction was. He had to break things apart under his claws until they were as busted up as he was.

But Aizen was watching.

"What are you doing, Tōsen?" He kept his tone level; inside his pockets, his fingers curled.

"Aizen-sama! Allow me to execute this man!"

What a load of shit. "Ah, this is a _personal_ grudge we're talking about. You just have a problem with me, don't you?" If he couldn't fight Tōsen, he was sure as hell gonna get _some_ satisfaction out of this. "Does that kind of attitude go over well in a commanding officer?"

Bark, little lapdog.

"I think I should not have to tolerate those who sow discord; that is all."

Bullshit. Bullshit, bullshit, _bullshit._

Grimmjow felt his mouth pulling up on the good side. "For the organization's sake, right?"

Tōsen held his sword level at his side. "For Aizen-sama's sake."

What a fucking idiot.

Grimmjow laughed—short and sharp like jagged glass. "You're good at hoisting up that great cause of yours," he said, sarcasm dripping from the words.

Tōsen was apparently tone-deaf as well as blind, though. "Yes. It is a great cause. Something missing from your actions. Justice without a great cause begets nothing but a slaughter."

Oh, for fuck's sake. He was getting a justice lecture. Grimmjow didn't bother resisting the urge to roll his eyes. It wasn't like Tōsen could see anyway. Actually, he kind of wished he _could_.

"However, that same slaughter in the name of a great cause—"

Tōsen vanished abruptly from Grimmjow's senses. Before he could so much as react, the feeling in his left arm vanished. Pain erupted halfway down his bicep; it wasn't until he heard his arm hit the ground that he realized what had happened.

"—is justice."

"Fuck!" Grimmjow lifted his hand to the stump, pressing the cloth of his ragged sleeve against it. "Fuck, fuck, FUCK!"

" _Hadō #54: Haien_."

Purple light shot from Tōsen's sword; Grimmjow watched his own arm incinerate. There's no way he'd get that back now.

"Fuck you!" He roared, reaching for his sword. "I'll fucking kill you for that, you fucking piece of—"

"Stop, Grimmjow." Aizen, without raising his voice, managed to cut over the noise.

Grimmjow, breaths short and blood singing with _rage_ and _pain_ , forced himself to turn enough to look at him.

"If you were to attack Tōsen here… I would no longer have any reason to pardon you."

Feeling his teeth grit so hard they creaked, Grimmjow forced his breaths to slow; he pulled them in through his nose and pushed them out through his mouth. Even to someone like him, what Aizen really meant was clear: _attack him and I'll kill you_. Even that almost wasn't enough; he had to squeeze the stump of his arm, letting the stinging pain slice through the angry fog clouding his thoughts.

Without another word—and before he could change his mind—he turned, stalking from the chamber.

No fracción, no left arm—

Someone was going to pay for this.

* * *

"My, my," Gin's voice drifted from around the corner at the bottom of the stairs. "Playin' with yer subordinates… that ain't a very nice thing to do, now is it?"

Sōsuke reached the landing and turned right, his tread carrying him right past where the other man stood against the wall. "You saw, then?"

Of course he had. Gin was reliably to be found wherever he shouldn't be.

"You knew right from the start that Kaname'd act that way if you kept eggin' 'em on, right? And Grimmjow, too."

"Hm," Sōsuke replied, lifting one shoulder nonchalantly. "Perhaps."

Gin fell into step behind him as he continued down the hallway. "And we lost five Arrancar, come to think of it."

"That is of no consequence." Grimmjow's fracción had been more loyal to Grimmjow himself than to Sōsuke. While they weren't enough danger to pose him any kind of threat, it was better to have everything under his control. He wasn't matched against a conventional opponent here; Kisuke Urahara had a rather well-documented tendency to be able to spin straw into gold. He knew better than to leave loose ends, considering that. "They were barely Adjuchas in the first place."

The Números were of little concern to him, ultimately. They were all designed to serve in this initial phase of things—when he met the Gotei 13 in full, they would hardly have a use to him. But for now… they would be the means to a very important end indeed.

"Find ten of the Números without fracciónes and have them stand by for deployment. And send Ulquiorra to me, please." Sōsuke paused. "…If he will not come out until he must… I will make sure he must."

Whatever threads that man was spooling out this time were better cut before the weaving.

* * *

Sōsuke turned the Hōgyoku over and over between his fingers. It had a strange presence, this fragment of god.

There was something overwhelmingly stifling about it, almost—threatening to render into stillness everything around it. Events, objects, even the very cells in his body. That was what had ultimately led to his understanding that it was incomplete, but now it made perfect sense. In time, he would present it to its other half, and complete it. For now, however, it was of more use to him as it was.

The one problem, however, was that it deteriorated slightly more with each use. Already it was difficult to awaken when he wanted it—he had to bring it into close proximity with the other to even make use of what it had to offer. He could not allow it to sustain much more damage than it already had—or else he would have to find a way to restore it to its undamaged state.

On that count, there was an intriguing possibility. That the potential solution would also serve several of his other aims at once was simply largesse on the part of fate. Having one way to do many things was as fortuitous as having many ways to do one thing—both had their place in his strategy.

"Aizen-sama."

Sōsuke lifted his eyes from the orb in his hand to Ulquiorra. He smiled mildly, crossing one leg over the other.

"Ulquiorra. Thank you for coming." The Espada disappeared from his vision for a moment as he closed his eyes, reappearing when he cracked them open.

"Of course." Ulquiorra himself didn't generally seem to have a need to blink; not nearly as often as anyone else, anyway. It was that rapid regeneration of non-vital body parts, most likely.

The others no doubt found it off-putting; Ulquiorra always had a little more space around himself than even higher-ranked Espada—the subconscious avoidance of the void that all living things exhibited.

"In a month's time, you will lead some of your fellow Arrancar on a… foray, into the Jūreichi. When that happens, I would like you to retrieve a certain item for me."

* * *

"It is not often you ask to see me, Sōtaichō." Unohana occupied the other side of his desk with an obvious ease, standing straight with relaxed shoulders.

Of all the people he had ever called into this place, only three ever felt so comfortable, and for different reasons. He'd once considered it a test of character; it said something about a person—how long it took them to wither in his presence.

She never did.

She withered for nothing at all.

That was fortunate. He contemplated her from underneath heavy brows for a time, slowly pulling his thoughts into line. He was no fool—the situation with Aizen would have to be handled carefully. A strategic misstep could spell a death now that they would be unable to afford later.

"The advance team has requested field assistance from the Fourth Division," he said. It was the fifth time they had done so over the past month of reports.

"I see," she replied. Unohana offered no more than that.

"You and your lieutenant must both remain in the Soul Society. But if there are other members of your division that would suffice for such a task, I would know of them."

Unohana blinked once; she rearranged her facial features into a thoughtful frown. "What sorts of injuries would they be dealing with?" The sharp look in her eye was enough to confirm that she was asking for more information than that.

It was impertinence, but that was in her nature. He chose to tolerate it from her as he tolerated its much more obvious forms from Shunsui and Jūshirō. Perhaps it was unfitting of a leader to have favorites among his subordinates. Genryūsai did not think so. It was only fact.

"The situation is escalating gradually. They are outnumbered by the parties of Arrancar that are sent to contend against them. The primary purpose of these incursions seems to be causing as much damage as possible. Death is never far from them." He folded his hands on the desk in front of him.

"Will they be receiving other reinforcement, or just whomever I send?"

"I will send two more vice-captains, but that is all."

"Is that wise? We know what Aizen intends with this—if we cannot even hold them back from the Jūreishi…" Her mouth downturned, but she was otherwise just as still as he.

"Creating an Ōken in the Jūreishi would take time. He will not attempt it until he believes everything else is accounted for. It is imperative that we protect Soul Society."

Her eyes narrowed; there was keen understanding there. "The other Ōken is here. In the Seireitei. And you suspect Aizen knows that. You think the attention on the Jūreichi might be a ploy to draw us away and strike while we are weak."

Genryūsai sighed heavily. He did not often feel his age—but sometimes, in the faces of those who bore theirs differently, he did.

"Do not allow that piece of information to leave this room, Unohana-taichō." He let the title weigh heavier than the rest of the words, dropping it off his tongue with gravity he knew she would pick up on. A reminder.

She smiled darkly. "Of course not, Sōtaichō." She paused. "I do not enjoy sending my subordinates into a situation like this without more adequate protection. I would prefer to go myself, but as that is not possible… yes. I will send two. And hope for Aizen's sake that they come to no harm." Her eyes fell half-lidded, obscured nearly entirely by their lashes.

He nodded. "Very well. Prepare them for departure via Senkaimon tomorrow morning."

* * *

Urahara's basement turned out to be a really good place to train. Then again, that was probably its original purpose.

They had to be careful with how much they did—any serious injury was more drain on the only person around who could do any worthwhile kaidō. Tessai was pulling a lot of weight around here; Karin could recognize that much. Hell, the couple times he'd had to come out and fight with them to round out their numbers, he'd been damn good at that too. He and Yoruichi seemed to be pretty close to bottomless pits of reiryoku, kinda like Zaraki.

The rest of them had to work a little harder just to keep up—or at least they seemed to get tired faster. Hence the training. The only way she knew of to do anything about her reiryoku threshold was to drain it and recover, over and over, as many times as she could. She and Renji were at it pretty much any time there weren't Arrancar around.

Bastards had been hitting them a lot. At first it had been about once a week. Now it was more often—Karin had no idea what the hell they were trying to achieve with it. But everyone said this Aizen guy was some kind of tactical genius, so she figured there had to be a reason.

Whatever it was, it was wearing her down. Even discounting the fact that she couldn't sleep for anything—that she woke up shaking and thinking she was going to lose the last thing she'd eaten—it still would have been bad.

She used Hisaku to knock aside Zabimaru's shikai. Her arms were shaky and practically shouting at her to rest—but Renji's blows were weaksauce for him, too.

"Ugh, stop," she said, sheathing her zanpakutō. "We're not getting anywhere with this."

It had been a nice distraction, but she needed to rest or she'd be completely useless next time the Arrancar showed up. Dragging a hand down her face, Karin let herself collapse onto the ground, throwing her arms out to either side of her. She needed to do cooldown stretches, but right now she just wanted to play dead for a second.

Renji sat next to one of her hands. He put her canteen next to her head; Karin mumbled something that she hoped sounded vaguely like thanks. She could hear him scratching his head, then a thud as he flopped down too.

They didn't talk. She wasn't sure if that was because they didn't need to anymore or just because they were both too damn tired. She let her eyes shut, the end of her sigh turning into a groan. She'd gotten a lot stronger in the past month; there wasn't much of a choice. And they were mostly successful in protecting the town—though there was suspicious property damage occasionally, enough that people were starting to wonder what was going on. Still… no one else had died. The Arrancar actually didn't seem interested in killing people.

It seemed pretty weird for Hollows.

"Hey."

She wasn't sure if Hitsugaya was talking to her or not, but Karin lifted her head anyway. Renji sat up.

"We're getting reinforcements tomorrow. Sōtaichō's orders."

"Finally. Please tell me there's a healer."

He crossed his arms, arching one eyebrow and looking down to make eye contact. "Two, actually. One of them is your sister."

Karin braced her hands on the ground and pushed herself upwards into a sitting position. "Yuzu? That's—" She bit her tongue.

The truth was, she didn't know if Yuzu could handle this. It wasn't that her sister was weak or anything, but… there was a really hard battle every couple of days. And it got really, really bloody. If Yuzu had to kill someone… Karin chewed her lip.

Hitsugaya looked at her flatly, then shrugged. "Unohana-taichō chose her. We're getting a couple more fighters as well."

"Yeah?" Renji asked. "Who?"

* * *

Yuzu hefted her medical kit over her back, settling it into place and making sure the strap lay flat over her chest. Handing the other one to Iemura-san, she smiled warmly. "Well, I guess we should go see who our partners are, right?"

Adjusting his sunglasses, Iemura nodded, and the two of them took off for the Senkaimon.

The Seireitei was mostly empty at this time of the morning—the sun was only just beginning to light the sky. The kidō lamps set at regular intervals along the main streets were going out, since nautical dawn gave them more than enough light to see by. Ahead, the massive stone arch of the Senkaimon loomed, attended as always by two officers of the Kidō Corps, their faces masked but for the eyes.

Already standing in front of the gate was a tall man Yuzu recognized as Tetsuzaemon Iba, vice-captain of the Seventh Division. Positioned next to him was Yachiru; upon spotting Yuzu, the tiny fukutaichō started to bounce on her heels.

"Zu-chan!" she called, waving both arms in the air. "I get to go with you to see Ken-chan and Ri-chan!

Yuzu was honestly surprised she hadn't been sent with Zaraki-taichō in the first place—but then she didn't really know anything about their battlefield dynamic. "It will be good to have you, Yachiru-san."

It wasn't like they were going on vacation—and Yachiru was vice-captain of the specialized combat division.

Iba cleared his throat, drawing Yuzu's attention. It was hard to tell behind the sunglasses, but he seemed to be… assessing them? Maybe. She drew herself up a little straighter, conscious that she was being sent with her captain's express confidence and permission. For as long as she was out there, she had to represent not only herself, but the capabilities of the Fourth Division. Her captain had not spared her from the truth—the others already over there were risking their lives, and she and Iemura might be the only difference between their living or dying.

"We'll be meeting the others at Kisuke Urahara's residence," Iba said, adjusting his zanpakutō in its sash. "Hitsugaya-taichō is in charge of the mission, and so all of us will be following his orders, for the time being. Remember that we go there not only to fight or to heal, but to win and to survive."

Yuzu nodded. "Yes, sir."

"Let's go."

* * *

Space was difficult to find in the Urahara Shop; by this point they'd had to reorganize pretty much everything. Yoruichi had moved the rest of the women in with her, putting Iemura and Iba where Matsumoto and Karin used to be. Tessai slept on the kids' floor; his room was converted for use as the closest thing they could get to a hospital area. Yuzu had delicately picked through some of Kisuke's things; she left the stuff she didn't recognize alone, but apparently there were some useful things laying around.

Yoruichi had told her to just take them. It wasn't like they'd see much use otherwise.

The reinforcement was good; they had enough people around now that they could safely institute a patrol schedule, and those with days off could train and recover as necessary. It helped to have people circulating in and out of the place, too—it wasn't meant to hold so many bodies comfortably. Even Yoruichi started to feel a little overcrowded at times. Meals had been moved to the basement, since that was the only space that could hold everyone at once.

Shinji had been in regular contact, too. His Visored still didn't want to reveal themselves, not in front of shinigami, but she at least had his word that they'd show up if things got too much for the others to handle. She still wasn't sure what end she was working towards here—Kisuke had been nonspecific as usual whenever they'd talked about this—but for now, beating back or killing Aizen's invasion teams was good enough.

At the moment, Yoruichi was nothing more than a cat on a roof. A lonesome one, at that—at least until she heard approaching footsteps.

Yuzu placed a shallow dish of milk down on a flat tile. "Tessai-san said you liked it," she said amiably. "We've just finished making refreshments for the others, so I figured you might like some."

Yoruichi blinked at her. She looked different, now—different even from four months ago. It wasn't her hair or anything so trivial as that. Rather, there was a slight confidence in the way she spoke that hadn't been there before. Not even when she was in battle or healing Jinta.

Dipping her head down to lap up a few swallows of the milk, Yoruichi thought maybe she knew where it came from. "Thank you," she said, raising her head and licking her chops several times. "Are they still going at it down there?"

"Mm." Yuzu shook her head slightly. "Zaraki-taichō got bored, and Yachiru-san was encouraging him, so now I think he's fighting Renji."

"I'm going to have to find more boulders for the basement, aren't I?"

Yuzu smiled at her. "Probably." She settled into a crosslegged position on the roof beside Yoruichi. For a moment, she seemed to hesitate about something, brows furrowing. "Um… is it weird if I pet you? I've just always liked cats, and it's the first thing I think of when I see one, so…"

Yoruichi chuckled. "I don't mind. It feels nice, actually—like getting a massage."

The young woman's hand touched her head softly, then ran down her back to her tail. Yoruichi arched up underneath it, nearly purring when Yuzu moved back up to her ears. "Oh, that's nice. Ishida-kun refuses to do this, you know. He swears up and down that it's inappropriate."

Yuzu's smile grew. "That doesn't surprise me." Shifting forward slightly, she unfolded her legs and dangled them off the roof. "He can be a bit fussy about that sort of thing."

 _Fussy_ , Yoruichi thought, was an excellent word for it.

"Yoruichi-san," Yuzu said, her tone sobering. "Can I ask you something?"

"You can."

Isshin's youngest rolled her lips between her teeth, then sighed softly. Her legs kicked back and forth in the air, rustling the fabric of the skirt her gigai was wearing. "Do you think… that we'll win this war?"

Yoruichi cocked her head to the side, glancing up at Yuzu's profile. "Why do you ask that?"

"I've noticed that no one really speaks about it in those terms," she replied. "When people talk about it at all, they talk about doing their duty to the Gotei 13, or protecting the Soul Society. Sometimes, when they're being really honest, they just talk about protecting their loved ones. If anyone mentions winning… they say that we should fight to win, or always aim to survive. But no one has said anything about winning the _war_."

She paused, biting down on her lower lip. "But I don't know if that's because they think that part will naturally follow… or because they don't believe it's possible. Do we win if Aizen-san dies? Or if we kill all the Arrancar? If we protect Karakura Town? Or is it something else?"

If Yoruichi could have grimaced, she would have. "You don't ask the easy questions, do you, Yuzu-chan?"

"I'm sorry."

She shook her head. "No, it's fine. The truth is… probably no one talks about winning because no one knows what it would be to win. Most people in the Gotei 13 have no idea what Aizen really wants. And if the Sōtaichō has his way, probably they never will. It's wrapped up in some of the biggest secrets in Soul Society. Secrets that most people go lifetimes without ever finding out. And the people who know the most are probably the least sure that we'll succeed."

"I'd be surprised that more people weren't demanding to know what was happening," Yuzu said, her tone heavy with sadness, "except it's not surprising at all."

"How do you mean?" Yoruichi asked, both cautious and curious at once.

"Well… there are more obvious things people could ask questions about, but they never do. Why is there a wall around the Seireitei? Who are we trying to keep out, or in? Why does none of the technology or anything we have make it out into the Rukongai? Why don't we shinigami ever do anything to make life better for people in Soul Society? All we do is keep things the same. It's important sometimes, but—"

"You should be careful," Yoruichi said gravely. "Part of the reason people don't ask questions like that is because the people who do tend to disappear after a while."

And she knew a hell of a lot about that, didn't she?

Yuzu frowned. "There are a lot of kinds of people who disappear," she murmured. "I think… I think one day they might make me disappear, too."

"Because of your zanpakutō?"

A wry smile twisted the girl's face. "Yes."

"…or because of my questions."

* * *

Ulquiorra elected to open the garganta in the same place as he had before.

This time, however, the force he took with him was for combat and retrieval, not scouting. Aside from the disgraced Grimmjow, whom Aizen-sama had sent along for reasons Ulquiorra did not need to know, he had four others, all drawn from the ranks of Espada. Apparently, it was time to give the three newest members a field assessment.

But the most important objective, it had been stressed, was to find and retrieve the item of interest from the possession of the shinigami here.

Stepping from the gate, Ulquiorra alighted easily on the ground.

"What now?" Yammy asked, looking around the field. "There's no shinigami here."

"We wait," Ulquiorra replied simply. "They will come to us."

They did not have to wait long. Within moments, the two shinigami that he sensed moving about in the town were moving towards them, and it didn't take long for the largest cluster of them in the area to begin doing the same. The second-largest cluster remained—as it always did—where it was. He suspected those ones would be roused to the assistance of the others by the time this was through, but they would be far too late to be of any consequence.

Ulquiorra shut his eyes, letting pesquisa alone feed him the information he wanted. They joined up in a cluster before moving the rest of the way towards his group. Grimmjow shifted restlessly behind him, audibly grinding his teeth. Ulquiorra took to the sky with a _sonído_ jump. The other Espada should be more than capable of handling this. If they were not, they would die. He had more important matters to attend to.

The shinigami emerged as a single unit: nine, in total. They had been reinforced just in time to die, it would seem. Two were yet missing—perhaps intended to clean up the mess when matters were concluded. Interesting.

Ulquiorra cracked open his eyes and glanced down. Grimmjow had immediately split off from formation to engage the largest of the shinigami. He had expected as much—Tōsen's report had indicated that was likely. The others took a little longer to choose. All of the shinigami immediately released their limiters. For several moments, there was disorder; the beginnings of a group confrontation split up more by circumstance than design. Wonderweiss, incomprehensible thing that he was, nearly succeeded in stabbing the Shihōin woman from behind with his hand, but Tsukabishi's kidō saved her just in time. They took the opportunity to engage him, splitting off partway from the others and taking to the air.

Ulquiorra drew a few looks, but he made no effort to engage anyone. They would be occupied enough even without his interference. He, on the other hand, had simply to wait.

* * *

 _Term Dictionary_ :

 _Haien_ – 廃炎 – "Abolishing Flames." Hadō #54. Fires an oblong blast of energy which completely incinerates the target upon contact.

* * *

Reviews always appreciated. :)


	5. Chapter Five: Hurricanes a-Blowing

_Content Warning_ : Death, abduction, and lots of violence.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Five: Hurricanes a-Blowing

* * *

This was bad news.

Tetsuzaemon had been briefed before arriving—he'd thought that would prepare him to face down these Arrancar. But to actually stand under the combined force of all their reiatsu… he gritted his teeth. There was no time to mess around here.

" _Shishōshiro, Akage_!"

The tantō in his hand grew several times over, curving upwards and spiking into two tines at the end. His opponent, the biggest Arrancar in the bunch, grinned and threw a fist forward. Tetsuzaemon caught the blow on the blade-edge of Akage, trapping it between the blade and the pick.

The ground beneath his feet gave way, cratering outwards from where he stood. The reiatsu pressure of this guy was just insane. Thrusting his blade forwards, Tetsuzaemon took a hard step in, bending the Arrancar's arm at the elbow. His zanpakutō's edge bit in deeper.

"What's this? You can actually cut me!" A thin line of blood ran down the big guy's hand—he didn't seem to care much about it though.

"Yachiru-san! Now!" Tetsuzaemon didn't want to waste the opportunity created by this guy being too busy looking down on them to take things seriously.

"Okay, Ibaba!" Yachiru drew her sword, tossing away the sheath carelessly. " _Asobe, Sanpo Kenjū_!" She swung her sword down, the blades of her two beasts moving not quite in unison.

The three cuts hit the same place on the Arrancar's back—for a minute, Tetsuzaemon was sure they'd done some real damage to him. But then he just rolled his shoulders out, throwing an elbow back fast enough to catch Yachiru by surprise. Her nose crunched under the blow, and she flew backwards several feet.

Tetsuzaemon stepped into _shunpō_ , reappearing in the air behind her. His free arm wrapped around her middle, stopping her movement; he set her back down on her feet. From this angle, it was easy to see that the blow she'd dealt the Arrancar was shallow, barely enough to even cut him.

He didn't ask if she was okay. Tetsuzaemon had been in the Eleventh long enough to understand that Yachiru was the vice-captain for more reasons than just the captain's attachment to her.

Yachiru put one of her hands over her broken nose, drawing it back and staring at the blood on her fingers. Flicking her eyes to the Arrancar, she narrowed them. Tetsuzaemon moved a step to the left when bright pink reiatsu started to collect in the air around her.

She lunged, the beasts in lockstep. Tetsuzaemon figured that was his cue to try and work out how to beat this guy. While Yachiru had him distracted, he flashed to the side, muttering a kidō chant and charging up his zanpakuto with reiatsu at the same time. Yachiru was keeping the Arrancar busy, quick strikes forcing him to use both hands to block everything she threw at him.

Reaching the end of his chant, he pushed more power into both his free hand and his blade. He had no idea how long the spell would hold a guy like this—he was hoping it'd be just long enough.

" _Bakudō #61: Rikujōkōrō_!"

Three beams of bright light closed in on the Arrancar, each spearing right through him. Tetsuzaemon followed up by swinging Akage in a broad slashing arc—compressed reiatsu flew from the end of the blade straight for the Arrancar's center mass. " _Tosshin_!"

Heavy wind blew back from the point of impact. Tetsuzaemon had to take a step back, grunting under his breath. Air moved in and out of his lungs, deep and steady like bellows.

When the dust cleared, the Arrancar had only one thin cut on his back, from shoulder to hip. It crossed over the one Yachiru had left there, deeper but not deep enough.

With a huff, their opponent pushed outwards with his reiatsu. Shattering the binding kidō with barely any effort, he turned to face Tetsuzaemon.

"That all you got, shinigami?"

* * *

"Only two? This is hardly worth my time…"

Rangiku would have rolled her eyes, but she was a little busy not dying. This Arrancar, whoever he was, was _fast._

He appeared right behind her; she heard the whistle of a sword slicing air. Ducking, the frowned as it hacked off the ends of a chunk of her hair. Better that than her _head_. Bracing a hand on the ground, she swept her leg around in a low kick. The Arrancar jumped over it, still holding his long sleeve in front of his mouth. Rangiku sprang away before he could try to behead her again.

Renji came in where she'd moved out, swinging with his shikai. The Arrancar knocked it away with his sword; Zabimaru clanged as Renji drew it back to its solid form.

This guy was way better than the usual Arrancars; it was obvious from the way he was acting—like they weren't even a challenge.

"Renji! We've gotta give this everything we have!"

He appeared next to her, both hands wrapped around his zanpakutō's hilt. Aside from a cut above one of his eyebrows, he looked fine—but their opponent was still playing with them. They had to try and beat him before he got serious, or they'd be in real trouble.

He nodded. "Cover me, Rangiku. Bankai: Sōō Zabimaru."

" _Unare, Haineko!_ "

Her zanpakutō's blade burst into ash; Rangiku turned the hilt. The stream flew directly for the Arrancar—only for him to skip out of her range.

He sighed theatrically, rolling his eyes at the both of them. "Really, I wish you'd all come at me at once—but if you insist on dying separately, I suppose I'll start with you two. _Kubire, Trepadora._ "

Rangiku nearly dropped Haineko's hilt when something thick wrapped around her neck, hoisting her into the air by the throat. It squeezed hard enough to cut off her air. Automatically, she reached up with both hands to claw at it, her feet kicking uselessly underneath her. Looking down the… _tentacle_ , she guessed, she saw the Arrancar—and seven more wiggling limbs.

It probably wasn't really appropriate to the moment, but all she could really think was that for a battle technique, it was really gross.

Turning Haineko's tsuka, she directed as much ash as she could onto the few inches right in front of her face, then cut. Like all of his kind, this Arrancar had tough skin—she tried to concentrate the ash in one area, but even that wasn't enough to break it off.

But the hold on her throat loosened a bit, and Rangiku gulped in as much air as she could. "Renji!"

"Working on it!" he called back. He was jumping between tentacles, obviously trying not to stay in one place long enough to get trapped like she was. Some of the things had spikes on them now; she really needed to get out of here before the Arrancar decided to use them on her.

Maybe—

The Arrancar squeezed again; the air she'd just pulled in was going to have to be enough for a while. Clamping down on her instinctive fear, Rangiku tried to keep calm, collecting the ash more slowly this time. She used it to cover an even smaller area—just a half inch, but all the way around the tentacle. She packed as much on as she could, accumulating it bit by bit.

Renji—spectacular distraction that he was—kept slashing at the other seven. She was pretty sure she could hear him yelling at the Arrancar, but she couldn't let herself get distracted, too. When her ash was as dense as she could get it and her vision was starting to get cloudy, Rangiku made a slashing motion with her sword's hilt.

It was enough; the arm holding her snapped back, and she dropped. Breathing through her bruised throat _hurt_ —like rubbing sand into a wound. But she had air again. Flashing away from the range of the tentacles, she steered her ash cloud to shield Renji from the side, making it solid it in front of one of them. But the Arrancar punched right through, barely slowing down, and slammed into Renji's back. He hit the ground, making a smoking crater where he landed.

It took him longer than it should have to get up again.

* * *

Tessai was quite disturbed by this Arrancar's childlike shape. He didn't really have it in him to harm children—but if anything had become clear over the last few minutes, it was that something was very, _very_ wrong with this one.

The boy didn't seem to be able to speak or communicate, and his attack patterns were almost entirely random. Against trained tacticians such as himself and Yoruichi, that was both an advantage and a disadvantage. But worse than that was the sheer strength of him—he'd already shaken off a Bakudō in the sixties. _Shunkō_ , which should have broken his bones, left only small mars on his skin.

"Seal him again!" Yoruichi lunged; fist charged with lightning, she swung for the boy's chest.

Recognizing the opportunity presented, Tessai complied. Crossing both middle fingers over the index ones, he brought his hands together. " _Bakudō #99: Kin_."

Tessai chose an origin point for the spell over the boy's shoulder. With a sound like a pennant in the wind, black fabric shot forward, wrapping itself around the Arrancar's arms and pulling tight until they were pinned at his sides. Metal stakes manifested above the cloth and systematically pinned it to the ground, holding him in place.

He hesitated. The boy was resisting; in time, someone with reiatsu like that would be able to break away. Perhaps even one of his allies would seek to cut him free. Tessai's eyes moved for a moment to the sky, where the more powerful of the two men from before continued to stand, unperturbed by the battles raging below.

If that happened, then this one would be a danger to all of the allies on the battlefield. There was no guarantee he'd simply continue to attack Yoruichi or Tessai themselves; he could choose a different target, and there would be no way to know it was coming.

And yet… he was still a child.

"Tessai! What are you waiting for?! We have to help the others!"

He sighed heavily. Yoruichi was most likely right. Whatever this boy really was—however he had come to be here—he was a threat to Tessai's friends, charges, and the Soul Society itself. He could not afford to be merciful. Swallowing thickly, he regarded the vacant face of the Arrancar.

"Farewell, young one. I hope you do not know pain."

Tessai raised a single hand, folding in the last two fingers of his left hand and holding it inches in front of his mouth. With heavy tongue, he murmured the words to the next spell. It would tear away the _Kin_ ; he had to make it strong enough to destroy the Arrancar as well. He and Yoruichi were needed elsewhere.

" _Hadō #99: Goryūtenmetsu_."

The pressure created by the spell's release flattened the grass, nearly knocking several of the nearest combatants out of the air. He hoped his allies would be swifter to recover than their foes. Around him, the ground trembled, quaking and rupturing. Five massive earthen pillars rose from the belly of the earth, forming a pentagon around him. The reiatsu he channeled into them converged above his head and became a massive dragon, made entirely of blue flame.

"Forgive me," he said, though he'd stopped knowing to whom he addressed such requests long ago.

With a sharp motion, Tessai dropped his left hand like a guillotine.

The young Arrancar's head tipped up and back, bathed in the blue light of the spell's fire. A beatific grin overtook his face.

"Aaaa." He opened his mouth.

The _kin_ broke, incinerated by the heat. Tessai, unable to see beyond that point due to the brightness of the spell, squinted. He had no wish to look away from what he had done—some things had to be seen. But his eyes couldn't tolerate the light, and he was forced to close them.

Behind his eyelids, he could see the spell recede, its purpose fulfilled.

"No way."

It was Yoruichi's disbelieving murmur that prompted him to open his eyes again. He stiffened, freezing in place.

"Im… impossible."

The flames of the spell had dispersed… and the childlike Arrancar was unharmed. His shape had changed—he stood far above any human being now, proportioned like a bizarre version of one of Ururu's paper dolls, and nearly as flat. At his shoulders and hipbones were grated vents, all issuing steam from somewhere within.

Tessai pulled in a breath. Two level 99 spells had put a significant dent in his reiryoku—he was more out-of-practice than he should be.

He wondered, now, if his years of idle contentment would cost him his life.

* * *

"Holy _shit_."

Karin kind of wished her fight had been a little closer to that spell. Maybe she could have shoved this Arrancar into it. It looked like it'd clipped half the tentacles off that one Renji and Rangiku were fighting, at least.

"Focus, Kurosaki."

Of course captain crabby didn't sound impressed, but she bet _he_ sure as hell couldn't do that. Her eyes narrowed, but she had to admit he had a point. This Arrancar they were fighting… he gave her the creeps.

To start with, he hadn't said anything. No words, no taunting, no _nothing_. Just creepy silence, even when swinging around that stupid bigass sword he had. He wore a dark cloak with ragged edges over the white uniform all the Arrancar had, but he was definitely more human-looking than most of them. His mask sat over most of his head like a helmet, topped with horns that curved forward from the back of it around his skull. The bottom half of his face was covered by a white zukin, making it impossible to tell what he really looked like.

She was pretty sure he hadn't used his resurrección or anything; at least he'd never said a release command that she'd heard. But he was _freakishly_ fast. She was already pushing _Tobase_ to the limit just to avoid being skewered. Hitsugaya hadn't wasted any time either, and gone straight for bankai.

Too bad they hadn't even been able to leave a scratch on this guy.

Taking some initiative, Karin flashed to the side, figuring Hitsugaya could work out what to do if she kept the Arrancar busy a while. Hisaku clanged against the big cleaver the guy was carrying; there was just no way she'd ever win in a contest of strength.

Karin swept her off hand forward. " _Aoge_!" Fire burst from Hisaku's blade; she aimed it for his face, trying to keep him blind.

He moved so fast she didn't even sense it—but Hitsugaya did.

" _Hyōryū Senbi_!" Ice surged from his zanpakutō, just barely catching the Arrancar on one of his legs.

Abruptly, he dropped a few inches, distracted for half a second. Karin seized the opportunity, directing the free flames still under her control for his other side.

Ice cracked and fell away; the Arrancar moved too fast for her to hit him. Forcing her flames to stop, Karin grimaced. Where the heck was he?

"Behind you!"

Karin threw herself forward, cold shrapnel pelting her back as the Arrancar broke through the hasty ice wall Hitsugaya put up behind her. She didn't make it quite far enough—the end of the Arrancar's sword slashed right across her shoulderblades. Tears sprang to her eyes against her will—Karin took a wild guess and flashed right, trying to lose him. She could hear Hitsugaya yelling, though she wasn't sure what he was trying to say, exactly. Her own heart was too loud in her ears for her to hear anything else.

Suddenly, her body jerked to a halt. Burning… it felt like she was burning. Slowly. Hitsugaya was staring at her with wide eyes—when had he gotten right there? Blinking, she looked down. Something cold protruded from the front of her uniform. But that was weird; why was she burning if it was cold? Touching it, she decided that it wasn't cold like ice. It was cold like steel. Like a sword.

Oh. So that was what had happened.

The Arrancar pulled his sword free of her body, and the world sped up again. Everything rushed by at a thousand miles an hour—and then it was all darkness.

Karin fell.

* * *

When her sister's reiatsu plummeted, Yuzu felt it—even halfway across town. "Iemura-san!" she called, standing and slinging her supplies over her back. "Please, we have to go help them."

Given that the battle was still active, Yuzu knew it was very dangerous to begin triage now. But she feared that if she didn't, her sister might die. She couldn't allow that to happen—no matter what.

Iemura's lips thinned, but it didn't take him long to nod. "Very well. When we get there, _don't_ leave my side unless I authorize it, do you understand? Not for anything."

"Yes, sir."

The third seat opened one of the shop's second-story windows, and the two of them jumped out. Immediately stepping into _shunpō_ , they ran breakneck for the big park where the others had gathered. Buildings flew by to either side with every jump, but Yuzu still felt like they were moving too slowly.

 _Hold on, Karin. I'm coming._

They burst through the tree line on ground level. Yuzu pulled in a sharp gasp—she almost couldn't believe her eyes. She'd seen plenty of training accidents and injuries, some of them very gruesome. But not a _thing_ she'd ever had to deal with had prepared her to face down the field of an active battle.

The air stank of blood and burning flesh; it was thick enough that she could taste it on the back of her tongue. The shinigami had a two-to-one advantage over the Arrancar, except for Zaraki. But there wasn't a single one of them free of injuries, and most of them had several. Slashes, stabs, reiatsu burns—oddly-angled limbs clued her in to broken bones, even. She pressed her hand to her mouth, taking a half step backwards. Yachiru's face was smeared in red; Rangiku's left arm hung uselessly at her side. Someone had slashed Tessai across the back.

"Kurosaki!"

Iemura's voice snapped Yuzu out of her haze, and she remembered why she was here in the first place. Running after her superior officer, she located her sister quickly.

Karin, face up towards the sky, had come to rest in a sprawl; her arms were flung out to either side of her. Nearby, Hisaku lay in the grass, automatically sealed by the loss of the energy to keep her released. Near the center of Karin's chest was a long stab wound; she was losing blood much too fast—Yuzu could see the dark puddle still forming beneath her.

Iemura dropped to his knees, hands already lit with diagnostic and coagulant kidō. "He got one of her lungs," he said, his tone crisp and efficient. "It's collapsing. Kurosaki: you're in charge of the flesh-knitting kido and keeping the lung inflated. I'll do the rest."

Yuzu's breaths were too quick in her chest—her throat was closing up at the sight of her sister like that. Karin, who had always been so strong. It was… she didn't look _right_ , broken like this. She didn't look like the sister Yuzu knew at all.

So this was what Unohana-taichō had meant, when she said it was impossible to describe a war to someone who had never been in one. War was seeing this—loved ones bloodied until they were strangers. It was knowing that you had to set their bones and knit their skin and prop them up with whatever strength you had, all so they could go out and break again.

Her lip trembled, but she forced her body to obey her will, kneeling on Karin's other side and channeling the kidō through her arms. It wasn't hard to find the collapsed lung; keeping it inflated was delicate. The best thing to do was make sure it expanded and contracted in time with the other one while Iemura siphoned the excess blood out.

Hot tears stung her eyes, but Yuzu didn't let them fall. She needed to see clearly, to sense everything that changed. Karin's life might depend on it. Karin, who had always, _always_ been there for her.

Yuzu couldn't fail her now.

* * *

Kenpachi's hands were slick with some combination of his own blood and Grimmjow's. Even without an arm, this guy was a helluva fun time. It almost made him want to cut his own off so they could be even. After all, the Fourth could always reattach it later.

But there was a fine line between really liking to fight and being a fuckin' idiot—and Kenpachi was pretty sure he knew where it was.

His blade bit into Grimmjow's leftover arm, bringing a spurt of blood to the surface—but the wound wasn't all that deep. He'd thrown away his eyepatch a while ago; the extra reiatsu was coming in handy. Their swords clanged together; both of them pushed at each other. Kenpachi was stronger—Grimmjow's feet lost grip on the ground. He jumped backwards so he wouldn't get knocked over; Kenpachi followed.

"I hate to cut a good fight short," he said, "but there's somethin' else I gotta do. So go ahead and die for me!"

Yachiru wasn't gonna last much longer. And the only thing Kenpachi cared about more than a good fight was Yachiru.

He was gonna rip apart that big one.

"Heh. Not fuckin' likely," Grimmjow replied. He threw himself into a jump, springing up over Kenpachi's head and bearing down with his sword.

Kenpachi swung his zanpakutō up and blocked, bending his knees to deal with the reiatsu shockwave. Grimmjow grinned; he had a couple of really damn pointy teeth. He musta bit his tongue or something, because they were all bloody red.

It was a damn cryin' shame that this had to end now. Loosing more of his reiatsu, Kenpachi forced Grimmjow to the ground—no more of that jumpy shit. They were gonna finish this with dirt under their feet. And probably in their damn faces, too.

"That's some nice pressure you got there," Grimmjow said, leaping forward for another round. "Maybe I believe you about being the strongest after all."

Kenpachi's smile cracked his face. "Don't bullshit me. You knew that already, or you woulda picked some other fight."

Their swords met so hard that sparks flew off the blades, that metallic screech he knew so well shaking in his ears. He was almost there—almost to his limit. Just a little more…

Time to end it.

* * *

It was certainly plenty of useful battle data.

Ulquiorra had to admit that the field test of Wonderweiss's resurrección was better than he'd expected. Previously, he had thought he might have to engineer some way of pitting it against the Kurosaki girl's zanpakutō. Such a thing would have been only an ember next to the flame Extinguir was made to contain. While a Hadō #99 from a master of kidō still wasn't the same, it was a much closer comparison. Wonderweiss appeared to have sustained no significant damage whatsoever from the attack.

Of course, that was a piece of information the Gotei 13 now had that they did not have before, also. But giving it to them seemed to be of no concern to Aizen-sama. Presumably because knowing what someone could do was not the same as having adequate countermeasures—not for them, anyway.

Likewise, Anzparrejar was encountering no difficulty, despite one of his opponents being a captain. In fact, he was the first to actually down a foe, though from the looks of things, several more of them were just about to drop. They continued to fight on with a tenacity that Ulquiorra did not truly understand; their situation was utterly hopeless. In situations like this, the rational thing to do was die as quickly and quietly as possible. But still they they offered up pointless resistance.

Aizen-sama had told him to expect something of the kind; in the end, even the depth of their desperation was more information. No doubt Szayelaporro would be occupied with it for quite some time. Ulquiorra saw little point in that, either—a meaningless diversion.

His unblinking eyes tracked the so-called item of interest across the field. She appeared to him to be of little consequence; another of the shinigami, frantic and embroiled in futile struggle. Still, orders were orders—and Aizen-sama's eyes saw even more than Ulquiorra's did.

It was time.

Applying _sonído_ , Ulquiorra dropped lightly to ground level, allowing his presence to register to both of the healers by coming to a stop not three feet from where they bent over the fallen shinigami.

The man noticed him first. "What—"

His hand was halfway to his sword before Ulquiorra moved. Drawing his own, he slashed upwards in a smooth motion, flaying open the shinigami's chest. He didn't kill him—it was better to leave at least one conscious witness to the rest of this.

"Girl."

She stared at him with wide eyes, but the spells in her hands held steady—she was still stitching the other one's body back together. Her lips parted, but he cut her off.

"Do not speak." He pointed the blade of his sword down, letting the tip of it sit half an inch above the man's neck. "This is not a negotiation—it is an order. If you speak, I will kill him. Nod if you understand me."

The girl swallowed thickly, but she nodded.

"Good." Ulquiorra didn't remove his blade, but he did allow his grip to relax slightly.

From the way her eyes darted to his hand, she saw it—which was the point. He felt a dull form of surprise when she did not relax even slightly in turn. Nor did she stop her work. Interesting, but ultimately inconsequential.

"You will come with me. You will not speak. You will not explain your actions to your comrades. You will not attempt to lag or escape. If you do any of these things, I will cut down all of your fellows, one by one. And I will begin with your sister. Do you understand?"

She nodded a second time. The light in her hands switched colors. Ulquiorra's eyes fell half lidded.

"You have ten more seconds. Beginning now."

"Kurosaki—don't…" the man was speaking.

Ulquiorra pressed the edge of his sword into his neck, just enough to break skin. "Be silent or her actions will not spare you."

Wisely, the girl elected to say nothing in response. After ten seconds had passed, she drew back; the light limning her arms extinguished.

She stood. Blood dripped from her hands, but it did not seem that she noticed. For a moment, she looked hesitant, but then she nodded again. In a smooth motion, Ulquiorra sheathed his blade.

"You will remain no more and no less than two feet behind me until I say otherwise."

Another nod. At least she was rational.

He stepped back into _sonído_ , maintaining a pace slow enough for her to follow in _shunpō_. Ahead of them, he opened a garganta. Pausing at the precipice, he turned to look back over his shoulder. It seemed _those people_ were finally on their way. Hardly a concern, but… there was no point in lingering.

"Espada," he said, catching the attention of the field in the process. "We're done."

* * *

Renji fended off another hit from the Arrancar—Luppi, he'd called himself eventually. Didn't these bastards ever get tired? Or was their power really so far above the Gotei 13's? He gritted his teeth; Rangiku was in terrible shape—if they didn't figure something out soon, they were all going to die.

The attacks suddenly stopped when the short one—the one who hadn't actually fought anyone—spoke. Renji risked looking up at him.

What the—was that _Yuzu_? She was standing right behind the Espada; her hands were curled into fists at her sides. If he had to guess, Renji figured that the look on her face was fear—but she was doing her best to hide it. But why the hell was she up there in the first place?

"Already?" The one fighting Tetsuzaemon and Yachiru didn't seem too happy that they were apparently leaving.

Actually—shit. He had Tetsuzaemon by the neck. Preoccupied by their own fights and then the interruption, it seemed none of the others had noticed yet.

"Yes, Yammy. We have what we came for. Now we're leaving."

Renji wasn't about to take his word for it. Flashing quickly to ground level, he shifted quickly back into shikai for the reach and swung at the Espada's arm.

Several things happened in rapid succession, then: first, the Arrancar holding Tetsuzaemon's neck squeezed—hard enough that the muscles in his arm flexed all the way up to the shoulder.

Second, Renji felt several bizarre reiatsu signatures appear in the area.

Third, Zabimaru hit his target, the force behind the swing enough to bite deep into the Arrancar's arm and scrape bone.

Fourth, the injured Espada struck forward with his other hand. It hit Tetsuzaemon with a heavy crack; a blast came after. The sheer pressure in it cracked Zabimaru at one of his joints.

Fifth, Rangiku screamed behind him. The sound cut off abruptly—like she was being choked.

And sixth, a bright light surrounded the Espada, lifting them away from the ground.

"Get away!" Hitsugaya shouted. "It's Negación!"

Renji staggered backwards, nearly falling over from some combination of haste and exhaustion. The light around the Arrancar flared, and then disappeared. With it went the Arrancar themselves, leaving behind a bloody battlefield and eight wounded fighters.

Tetsuzaemon was not among them.

His reiatsu was completely gone—nothing but reishi particles in the air.

Yuzu Kurosaki had stepped into a garganta behind an Espada.

And Rangiku—

"Well… we're a little late, looks like."

Renji whipped around. A tall, thin blond man held an unconscious Rangiku around the waist. His sword dripped red, but… was that a _zanpakutō_?

The man tipped his head sideways. "You seem confused. Let me explain."

* * *

 _Term Dictionary_ :

 _Akage_ – 赤牙 – "Red Tusk." Tetsuzaemon Iba's zanpakutō. A melee-type that looks a little bit like a falchion—but with less curve, an oddly-shaped point(s), and a picklike protrusion a few inches from the end. It was never named or given a release command in canon, but the appearance is specified, so I filled in the rest. Released with the command _shishōshiro_ (刺傷しろ), the imperative of "to puncture." It can attack from a distance with compressed reiatsu using the technique _tosshin_ (突進), or "rush."

 _Sanpo Kenjū_ – 三步剣獣 – "Three-Step Sword Beasts." Yachiru's zanpakutō. There doesn't actually appear to be a canon release command, so I went with _asobe_ (遊べ), the imperative of "to play." Because it's Yachiru. The shikai leaves her sword unchanged, but manifests two creatures to attack with her, one before and one after, making her strikes really hard to avoid.

 _Trepadora_ – 蔦嬢 – Kanji for "Ivy Girl," Spanish for "Climbing Vine." Luppi's resurrección, which gives him eight white tentacles, all anchored at his back. The release command is _kubire_ (縊れ), "strangle."

 _Kin_ – 禁 – "Prohibition." The weaker version of Bakudō #99 (which is still like… a pretty insanely strong spell). Causes the target's arms to be bound to their bodies with spiritual fabric and then to the ground with metal stakes.

 _Goryūtenmetsu_ – 五龍転滅 – "Five Swirling Dragons of Destruction." A.k.a. 'Tessai is legit, y'all.' But actually it's Hadō #99. It creates a big ol' dragon in the sky to attack things with. It's actually not specified that it's a fire-based attack, but I went with it for drama.

 _Hyōryū Senbi_ – 氷竜旋尾 – "Ice Dragon Swirling Tail." One of Hitsugaya's many bankai techniques. It's the basic "arc of ice" variety.

 _Extinguir_ – 滅火皇子 – The kanji are "Prince of Extinguished Flames." The Spanish is "To Extinguish." Wonderweiss's resurrección. It's actually not clear in canon whether it can put out any fire or just Ryūjin Jakka's, but it'd be kind of weird if it could stop the most powerful zanpakutō in Soul Society but _not_ lesser flames; so I've decided that for my purposes, fire from any source falls under the scope of his ability.

* * *

So there's the un-twist. I figure a lot of you probably called Yuzu being the one to get abducted here, but I have some stuff in mind that I think makes it pretty clear she's not just a fill-in for Orihime on this. I mean… Aizen wanted her for similar reasons, but it's gonna work out… differently, I think.

And our first character death! I have nothing against Iba, by the way; but he was realistically pretty outmatched against Yammy, even unreleased Yammy, and the whole point of this chapter was that Aizen sent a team that could _really_ lay down the pain. Yuzu's decision to cooperate with Ulquiorra should make reasonable sense, considering the situation; that was necessary because she's a reasonable person who wouldn't ordinarily give up without a fight. (And probably never if Karin was still in danger of dying.)

As for Anzparrejar… why yes. I did invent an Arrancar (and a silly silly name to fit the theme). For reasons. Those reasons are not to steal the spotlight though—hopefully what I mean will be obvious enough in time (but not too obvious yet!)

Also… this series is now well over 200,000 words in total, which is kind of a big deal to me. Especially considering I started a month and a half ago. I dunno; I'm a _little_ proud of myself, I guess? :)

* * *

As always, thanks for reading.


	6. Chapter Six: An End is Coming Soon

_._

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Six: An End is Coming Soon

* * *

It was with the knowledge that they'd been soundly beaten that the remaining members of the advance guard made their way back to the Urahara Shop.

Tōshirō knew he should probably be pressing this Shinji Hirako for more information than he'd given; clearly, he and his followers carried zanpakutō. That alone was enough to inspire caution. But Shihōin obviously knew them—obviously trusted them to at least some degree—and so for once, Tōshirō didn't jump into the situation headfirst. In fact… he was fine letting her handle everything for now.

They dragged themselves inside, more or less. The people following Hirako left. Tōshirō put in just enough effort to memorize their reiatsu signatures, in case it became important later—but that was it. He parked himself in a corner of the medical treatment room; he was injured, but bandages and ice would do until the others were healed. Matsumoto, Iemura and Kurosaki especially.

Tsukabishi and Shihōin worked in efficient concert—Tōshirō wanted to do something to help, but it was obvious he would only be in the way if he tried to intervene at all.

Shihōin swiftly untied Matsumoto's sash; Tōshirō stared fixedly at the wall, but he didn't leave the room. Apparently not set on making him, they gave him updates instead.

"She's stable," Shihōin said briskly. "She's been strangled, and a few of her ribs and right arm are broken, but she'll be okay. I'm just going to bandage her for now and give her a painkilling injection. Tessai will get to her with kidō when he can."

Tsukabishi, bent over Kurosaki, grunted—probably an agreement.

One of Hirako's group had stopped Iemura's bleeding, but he was still out cold in the next room. Zaraki had several wounds, but nothing life-threatening. Kushajishi had broken her nose, left leg, and three fingers, but that was the worst of it. Abarai had already splinted his own wrist and wrapped his torso in bandages with only minimal assistance.

Iba was never coming back.

The other Kurosaki had been captured—or else defected. But that seemed extremely unlikely. Particularly considering that there had been only one death. It was too strange, considering how many more there could have been. The Arrancar he and this Kurosaki had faced… hadn't even released his zanpakutō.

Tōshirō's fingers curled into his palms. One taken by the enemy. The other fighting for her life not five feet from where he sat.

He didn't want to think about what Kurosaki-taichō would say.

* * *

While the others were either healing or waiting to get it, Renji kept his eye on Hirako.

There hadn't been much actual explaining yet—and there was no way he was gonna let some stranger with a zanpakutō wander around the place while nearly all of his comrades were injured to the point of being helpless.

"Jeez; you some kinda guard dog or somethin'?" Hirako was clearly aware of the way Renji tracked his every move.

"Somethin' like that," he replied.

He had to resist the urge to scratch his injuries—they were disinfected and bandaged, but it would still be stupid to pull at them. And his wrist was broken. He'd gone through Iemura's medical kit when they got back and taken care of himself; he knew how to use most of the stuff in the basic field pack.

He'd have to remember to thank Isane for that, if he ever made it back to Soul Society.

Hirako sighed too loudly and raised an arm to scratch at the outside of his ear with his left pinky. "You got it all backwards," he drawled. "We ain't the ones who put yer friends on the ground."

Renji scowled. For a moment, he glanced down at his broken shikai. Zabimaru was in two pieces on the floor next to him; he wouldn't be able to fix him until his reiatsu came back to normal levels.

"You sure as hell waited long enough to show up."

"Don't mistake me, kid." Hirako shot him a sly glance from the corner of an eye. "We don't owe you or the Soul Society a damn thing."

"Not even for those zanpakutō you have?"

" _Especially_ not for that."

Sighing, Renji winced when doing so twanged his ribcage. Oh right. Injuries. "You gonna tell me what the hell is going on or hint cryptically for another few hours?"

Hirako, looking obviously unimpressed with his lack of patience, rolled his eyes and crossed his arms. "Fine. But yer just gettin' the short version. I wouldn't bother, 'cept Yoruichi would even if I didn't… and you'd better hear it from one of us so ya get it right."

* * *

"You know, Gin, the Negación wasn't really necessary. The Espada would have managed quite well with the garganta." Sōsuke knew the real reason his subordinate had activated the rescue mechanism; it certainly hadn't had anything to do with saving the _Arrancar._

Gin's uncanny grin only widened. "Well, I kinda figured they were takin' too long. If they'd stuck around until them Visored showed up, we mighta had a few more dead ones."

Sōsuke let his eyes fall half-lidded. "In that case… I applaud your foresight. I would hate to lose any of my treasured subordinates for such… mundane reasons."

Just then, new reiatsu flared to life outside the throne room. It would seem Ulquiorra and the girl had made their way through the garganta at last. Without pausing to inform Gin of what he was doing, Sōsuke left the control room, headed for the stage.

He had to greet his newest guest, after all.

Gin followed regardless; they stepped onto the raised dais at the end of the chamber. Below waited the other Espada, both those rescued by the Negación and those who had not gone to the living world in the first place. All of them bowed as he took his seat, settling his shoulders back against the cold stone. Almost absently, he caressed one of the armrests with a fingertip—smooth, like marble. Or age-worn bone.

Waving his Espada back to their positions, he assumed his usual posture, shrouding himself in easy nonchalance and veiled—but barely-perceptible; that was important—menace. Fear was most effective when the ones afraid weren't quite sure _why._ That anxious dread, half-formed at the pit of a stomach, was what he wanted. If it were too-easily understood, it could be overcome.

That, after all, was how he had overcome his own.

No being here but him was permitted to be without fear.

The doors at the far end of the hall, vaulted almost to the ceiling, creaked open slowly. Ulquiorra entered, hands in his pockets and spine straight as an arrow. Behind him walked a young woman—she was scarcely more than a child. But she _was_ more than a child.

What a peculiar picture she made. Short, but holding herself tall. Hesitant, but walking in precise, efficient lockstep with Ulquiorra's pace. A clean shihakushō; bloody hands. Alert, but with eyes that didn't waver from him. Not from the moment she stepped into the hall.

Admittedly, Sōsuke rather enjoyed that.

He was hardly surprised it had come to this—she was one of the Kurosaki children, after all. He'd known about every one of them from the moments of their birth.

He had initially deemed this one the least significant of the three. The boy had inherited their mother's more _interesting_ traits, and her sister had—to all indications—the lion's share of Captain Shiba's legacy.

And yet.

Sōsuke's lip curled into a placid smile. "Welcome to Las Noches," he said softly.

She swallowed, thickly enough that he could see it even from where he was.

"You are Yuzuki Kurosaki, correct? Or perhaps I should say Yuzu?"

Her brows furrowed; he watched confusion flicker over her face. _How does he know?_ _Why does he care? What does he want?_ —he could read it all in the way her pupils contracted, in the line etched into the skin above her nose. He read even more into the deep breath that raised her shoulders and shifted them back, in the way she lifted her chin to speak to him.

"I suspect," she said quietly, "that you will call me what you please, Sōsuke Aizen-san."

Kaname shifted on his left. Sōsuke's smile lost all semblance of subtlety, spreading slowly across the whole of his face. He lifted one eyebrow, just a few centimeters.

"You suspect correctly," he granted. "I'm sorry to be so forward, Yuzu, but you see… I brought you here to make a request of you."

She folded her hands in front of her, clasping them together. He let the silence stretch just long enough to become uncomfortable. As he'd expected, she found her tongue again and broke it.

"I see," she said. "And what might that be?"

"You're a member of the Fourth Division in the Seireitei, aren't you?"

Her jaw flexed momentarily. "Yes."

"And that division is responsible for healing injured shinigami, isn't it?" Sōsuke didn't look at the assembled Espada; he knew they waited with varying degrees of patience for him to explain what this little shinigami was doing in their midst. He also knew some of them weren't going to last much longer.

"It is." She still watched him warily; like a mouse waiting for a cat to make any kind of movement.

"Well then. I would like you to demonstrate what your division has taught you, if you would?"

She clearly paused to consider that. As he'd expected, of course, one of the Espada cracked first.

"Aizen-sama. May I speak?"

Sōsuke's smile faded; he turned his eyes on the temporary Sexta. "You are displeased by something, Luppi?"

"Of course I am," he said, barely maintaining the façade of respect most of them deemed necessary in his presence. "Who _would_ be happy that the entire fight we just had was nothing but a smokescreen to lure out this girl?"

"You have my apologies," Sōsuke said mildly. "I did not expect a few shinigami to prove so troublesome to four Espada and two Números."

Luppi glowered and bit his tongue. Predictable. Returning his attention to the girl, Sōsuke continued.

"As I was saying, Yuzu, I would like you to perform an act of healing for our edification. Perhaps…" he trailed off, flicking his eyes to a bloody Grimmjow. "You could repair the damage to Grimmjow's arm."

Grimmjow himself straightened, eyes rounding in textbook surprise. _It is not possible_ , said the look, and the looks of everyone else in the room.

Except Yuzu.

"Ridiculous!" Luppi proclaimed, overconfident as usual. It was tinged with desperation, though; he knew what might happen if Grimmjow's arm _did_ return. "That's impossible, Aizen-sama! Grimmjow? Tōsen-san reduced his arm to ash! She can't heal something that doesn't _exist_ —she's not a god!"

God? No. No one would bear that name but himself. But she was close enough for present purposes.

"Am I permitted to release my zanpakutō?" The girl's question was just as softly-uttered as everything else she had said—but he detected no doubt in it.

"For now."

She nodded, drawing a short blade from inside her sleeve. Unusually for a sealed tantō, it had a tsuba, if a small one. Flower petals. How apropos.

"Hey! Are you listening, girl? If this is some show to save your ass, you'd better knock it off!" Luppi's agitation only increased when no one paid him any attention.

" _Sakisomero, Hasuhime_."

Ah, he'd heard about this.

Sōsuke considered himself a man of refined sensibility and discerning taste. It was important to understand the details, after all, when one needed to shape them to fool others. So he had no issue rendering aesthetic judgement on the zanpakutō the girl carried—it was quite the sublime thing, the way it worked on almost every sense like that, simply in the act of release.

More sublime still was just how perfectly it was going to work for his ends, of course.

Unhesitatingly, Yuzu moved to Grimmjow's left side. The Espada himself blinked at her, his eyes narrowing. More curiosity than hostility—that was unsurprising. She presented no threat to any of them. Tilting the pole, she braced it on her shoulder, the rings chiming as it settled.

"I don't know if this will hurt," she admitted.

"If you can't do it, I'll kill you!"

"Will you _shut up_? Some of us are trying to collect data here!" Szayelaporro lost patience with Luppi, rounding to face him with a glare.

"Screw you!" The Sexta shot back. "I don't have to do anything you say!"

"If I second the request, do you have to stop shouting?" Starrk rubbed his right temple with the same hand.

"It's working." Ever a woman of few words, Harribel redirected the group's attention to what was already obvious to Sōsuke.

Yuzu had removed the bandages on Grimmjow's stump, letting them fall to the floor. What looked superficially like magenta kidō enclosed first her hands, then the rest of her, in translucent light. Carefully, she touched Grimmjow's bare skin, drawing her hand down the empty space an arm would have occupied if he'd had one.

Reality, to all appearances, obeyed the implied command. Interestingly, it was bone first. For a few amusingly-grotesque seconds, everything below the Arrancar's shoulder was skeletal, held together with more of the light. But then from the stump—layer by layer—grew muscles, sinews, nerves, and finally, smooth, unscarred skin. Grimmjow flexed his new—for indeed it _was_ new—arm, mouth slightly open.

"H-how? I've never heard of anything at that level. How did she…?" Luppi shook his head. "How did you _do_ it, woman?"

The girl stepped away from Grimmjow. Her eyes moved to Luppi for only a moment before she flicked them warily back to Sōsuke. She wondered if he knew—and didn't want to say. Logical, but ultimately irrelevant. He had deduced the nature of her power even before she had.

"It looks like a temporal or spatial regression, doesn't it?" It didn't, really—but most of his underlings were not discerning enough to understand what the signs of such a thing would even be. Sōsuke asked mostly so he could see if she showed any sign of hope. Hope that she might go undiscovered.

It was almost impossible to see—she hid it remarkably well, for someone in her situation. But he saw it nevertheless. He was going to take satisfaction from crushing it.

"But that's—shinigami aren't allowed to do that!"

"Correct," Aizen replied. Though that didn't stop all of them, of course. Nevertheless… "But this is neither of those. This is… the abolition of limitations."

Yuzu stiffened. Aizen's smile returned.

"Her power is to select a target parameter—a limit on natural existence placed down by god—and to remove it. The laws of nature say that kidō may only be cast in certain forms, but she may choose any she desires. The laws say a body can only withstand so much of Hell's energy before succumbing to damnation, but she can increase the threshold and make a body reject as much as it needs to. An Arrancar such as Grimmjow has a limit on what damage his body can recover from—but she can destroy that limit so that he might regrow an arm, a leg, or even his heart, if necessary."

She denied nothing; it would be meaningless to do so anyway.

"One might say that she asks god to change its mind… and god has no choice but to agree."

"One might," she conceded. "But I think that would be an overstatement."

"We shall see."

* * *

Kenpachi sat down in front of the wall with a grunt. Even he was pretty fuckin' wiped from all this shit. That guy from the Fourth was back up and at 'em, so only the Kurosaki girl was still down—but Kenpachi figured she had the right, on account of the fact that she'd been stabbed clean through. They were short two people other than her, though.

Then there were those weird guys with the masks. But they were a buncha dumbasses who couldn't be bothered to do shit, so Kenpachi didn't really feel like counting them. What were they called again? Vizard… Visored… somethin' to do with masks or whatever. They could stick to their end of town if they wanted, but that was about all he was gonna waste time thinkin' when it came to them.

"Ken-chan, I wanna take a nap." Yachiru yawned to prove her point.

It was the middle of the afternoon and raining, so normally he would have been thinking the same thing. Yachiru had her head on straight that way. But it was his job to be awake right now or something—most of the others were out on patrol or resting in the other room.

"So take one," he told her. "Ain't like you gotta ask my permission."

She crawled into his lap. Kenpachi leaned back against the wall behind him, shifting to make room for her to put her back to his stomach. This kid was the weirdest. He knew he scared the shit out of pretty much everyone he met. Sometimes he even did it on purpose. Most of the time, it was just… something that happened.

But Yachiru had never been afraid of him. Neither of 'em had, come to think of it. Maybe that was why he'd thought of that name first when he met this one. Sure, he admired the first Yachiru—but it was the not being afraid that they really had in common. He didn't know what it was about them exactly, but he didn't bother thinking too hard about it. It was what it was.

By all rights, he should scare the skin off any little girl in a fuckin' ten-mile area. But this one stood up against enemies that made grown men shit their pants.

She leaned sideways, tucking her legs against herself and resting her head on his knee. "Ken-chan?"

"What?"

"Ibaba saved me."

"Yeah?" He knew 'Ibaba' was her name for Tetsuzaemon.

She nodded into his hakama. Kenpachi frowned. She wasn't normally like this.

"The big stupid was gonna get me 'cause my leg was broken. But then Ibaba got in the way and the big stupid got him instead." Yachiru spoke slower and softer than he'd ever heard her.

Kenpachi heaved a sigh. Really, only this kid…

He picked up a big, rough, scarred hand and set it on her head. "Sometimes, ya gotta do stuff like that, Yachiru. Tetsuzaemon knew what he was doin'."

"It's my fault Ibaba died, isn't it, Ken-chan?"

The bells on Kenpachi's head jangled when he shook it. "No, Yachiru. It ain't. That's between him and the big stupid." He moved his fingers back, pulling some of the pink hairs from her face and putting them behind her ear. His calluses dragged against her cheek; he pretended not to notice that they came back wet.

"Is Ken-chan gonna die, too?"

Kenpachi scowled. "'Course not. Who do you think I am? I'm Kenpachi Zaraki, the strongest guy in Soul Society."

He dropped the volume of his voice till it was mostly a rumble in his chest. "I ain't goin' nowhere, Yachiru. Now take your damn nap already."

She smiled against his knee.

* * *

It wasn't until halfway through the day after the battle that Karin woke up.

If anyone had asked Rangiku, she would have said that she was probably going to be really upset when they broke the news to her. And not upset in the teary, sobby way.

But nobody had asked Rangiku.

"What do you mean, she's gone?!"

A crash—something ceramic, maybe—came after that. Rangiku poked her head out the door of the girls' room. The room across the hall where they kept the medical stuff was open. Through the doorway, she saw Karin struggling to her feet. Iemura had a weird half-grimace on his face; he was holding his arms out like he wanted to tell her to lay back down, but couldn't quite get up the guts.

Rangiku couldn't really blame him—the girl was literally _steaming._

"Kurosaki, get ahold of yourself!" Tōshirō, who'd been sitting at his post in the corner of the room, stood up. He didn't look too excited to try and bodily make her sit either, though.

If it were any other situation, Rangiku would have found it funny. But it wasn't, sadly.

"Get ahold—" Karin's mouth made words that wouldn't come out for a few seconds. "Are you fucking kidding me?! I get stabbed by a goddamn Arrancar and wake up to find out that in the _one day_ I've been out, Iba died and they _took my sister_ and you wanna tell me to _get ahold of myself_? Fuck you!"

A cloud of frosty air met the steam; the reaction only started to fog up the whole room. Before things could get any worse, Rangiku figured she should do something. Too bad Renji was on patrol right now; she wasn't sure she could handle both of them at once.

"Hang on, hang on, let's not do this here." She left off the careless breeziness she usually used—that would only make things worse.

Instead, she stepped into the doorway, making a show of fanning away the mist. Both of them seemed to realize what they were doing at the same time. She saw the captain's hackles go down first, so to speak—he settled himself back on his heels and relaxed his shoulders. He always stood on the front part of his feet when he was ready for a fight—Rangiku thought probably he did it without knowing. It _did_ make him a bit taller.

Karin was a tougher nut to crack. But she at least took in a deep breath through her nose. The heat on her side of the room cooled a little. "We have to go get her back."

Tōshirō opened his mouth to respond. Rangiku met his eyes and shook her head slightly, hoping he'd let her handle it. He scowled even deeper, but shut his mouth with a click of teeth.

"I know that's what you want to do, Karin-chan."

Karin started to stiffen again. Rangiku hurried to cut her off.

"But there's actually no way to do it. I'm not sure what you were told, but… Yuzu-chan went into a garganta. That's a portal directly to Hueco Mundo, and we don't have the capability to open those. The technology doesn't exist."

"Can't we just use a Senkaimon? Or what about Yoruichi and Tessai? They have an illegal one—they even had a gate to Hell in here once! They have to know how to open one!"

Rangiku blinked. "Gate to… Hell? Really?"

Her captain looked just as surprised as she did. Hell wasn't connected to Hueco Mundo, as far as Rangiku knew; but then again, the things she knew about it could be counted on her fingers.

"I can't help you with that."

Rangiku stepped in and to the side to let Yoruichi through. The other woman crossed her arms, glancing at the broken vase for a moment before returning her eyes to Karin.

"Kisuke might know how to do something like that, but he's not here, as you know. I wish I could help you, Karin-chan. But the only ones who can open gargantas are Hollows of the Menos class and some of those Arrancar."

"So? We catch one and make it open a garganta for us."

Yoruichi grimaced. "The thing is… I'm pretty sure those Arrancar came here for the _purpose_ of taking Yuzu. That means we might not see them again for a while. But. If they wanted her specifically, that suggests Aizen has a reason to want her around. Which means…"

"Her life isn't in danger until that purpose is fulfilled," Tōshirō finished.

Yoruichi nodded. "I know it's not what you want to hear—"

Karin scoffed, worry and anger fighting for dominance on her face. Rangiku knew a few things about that combination.

From where he sat, Iemura cleared his throat. "She went to save the rest of us," he said, laying his hands on his knees. "That Espada, the one who didn't fight—he threatened to kill everyone if she didn't cooperate. I have worked with Kurosaki-kun for two years now. I can say with confidence that she is more than she appears to be. And she knows it. We should believe in her, and wait until we can bring her back."

Rangiku bit the inside of her lip. The only thing about that was… she didn't know if Soul Society would ever even _consider_ a rescue mission. Yuzu's life, precious as it might be to her friends and family, was only one in the millions at risk.

But it was a bad idea to say that. There was literally nothing they could do about this—unless someone managed to figure out how to open a garganta or another Arrancar appeared.

"Then what… what do we _do_?" Karin flinched, pressing the heel of her hand against her chest.

Yoruichi looked at her for several long moments. "You rest up for a few days. And then you're training with me. Rangiku-san, Tessai has a few kidō he wants to teach you. Whatever comes next, it seems best to be as strong as possible."

Even Rangiku, who hated training, couldn't disagree with that.

* * *

They didn't seem to be too fond of doors, in this Las Noches place. Or maybe that was just in the case of captives. The throne room had a door on it, after all.

After Aizen had decided he was done parading her around in front of the Espada, he'd stuck around just long enough to watch the one called Grimmjow kill the one called Luppi. Honestly, Yuzu had been horrified, but at the same time… it had made her think.

And she was still thinking, now, here in this big white room with the barred window near the ceiling. The door was narrow, so she could escape view from the hallway if she really wanted. No one seemed to wander by, anyway—the impression she had of this place was that it must be absolutely huge, and mostly empty.

Aizen had said they weren't to hurt her, but that rule only held as long as she didn't release her zanpakutō. At least they hadn't taken Hasuhime away from her—it was a relief.

Was she supposed to think that?

Still in shihakushō, she plopped down in the center of the pristine white couch in her room. She'd never pictured Hueco Mundo as the kind of place that had couches. Or giant castles, for that matter. Maybe her imagination was just bad—had she thought that Hollows sat on the ground all the time?

Thoughts swirled around and around in her head: thoughts about her situation, about Karin and the others, about her friends and family in Soul Society, and about inconsequential things like Arrancar furniture. She was tired, and she was a mess, but she didn't think she could sleep just yet.

So, relaxing back against the sofa, she tried to sort everything out. An ordered mind, said Kozu-sensei, was the first step to anything important.

Yuzu pushed all the random ones to the side first, deciding she could worry about the smaller implications of everything she'd just seen later, when she'd worked out the rest. Much as she'd prefer to remain with her memories and warm feelings for her loved ones, she pushed those aside, too. All they would do right now is distract her. She felt an overwhelming urge to curl up here and sob until someone came to rescue her; but, if she waited that long, she might never leave here alive. Her history lessons had been clear: no one got in or out of Hueco Mundo without a garganta, and only Hollows could make gargantas.

So… she had to figure out how to survive. She wasn't sure what these people were expecting of her, but Yuzu was a Kurosaki. And a Kurosaki never gave up, no matter what.

"Right," she muttered.

Pulling her legs up underneath her, she collected what she knew.

She knew Aizen wanted to use her power for some purpose. He'd made that plainly obvious by sending an Espada to kidnap her and making her demonstrate what she could do in front of all his underlings. He wouldn't have shown them that if he didn't want them to see, and he wouldn't have explained it unless he wanted them to _know_. But he hadn't come right out and said what he really wanted her for, even then.

She considered the idea that it was just what he'd already made her do: healing. Yuzu chewed her lip. It was true that she could do that; but it didn't seem right. Surely they had healers here. And if that was all they'd needed, they'd have taken Iemura-san, too. Hasuhime's _Bensakujo_ technique made certain things possible that wouldn't have been otherwise: that was true. But if all he wanted was healthy, functional subordinates, he wouldn't have let Grimmjow kill Luppi like that.

So it was something else.

"Girl."

A voice broke her train of thought. Yuzu frowned; she should have still been aware of reiatsu, but she'd failed to pay enough attention to sense him coming. It was the one with the green stripes on his cheeks; the one who'd brought her here.

She tilted her head at him.

He stepped inside the doorway, setting a tray down on the endtable next to the sofa. "Eat."

Yuzu didn't see any point in refusing. Keeping her health was paramount. Standing, she moved over to the tray. Rice, fish, and miso soup, from the look of it. It smelled pretty nice, too. There was even an apple in one corner of the tray, next to a cup of steaming green tea.

"There's a kitchen here?" she asked, glancing at the Espada.

He didn't reply.

She sighed slightly. Perhaps she should be afraid right now. She had no doubt that this man—like all of the others she'd seen here—could kill her without breaking a sweat. But obviously Aizen wanted her alive, so for the moment… being afraid would just be a waste of energy.

There was a chance the food had something in it. That… was a chance she had no choice but to take.

"Thank you." Being polite probably wouldn't hurt her odds; it'd be harder for her to be rude anyway. "Umm… I don't know your name."

He didn't blink often, she noticed.

"You don't need to," was all he said.

Yuzu sighed again. "No, I suppose I don't."

He left her.

Picking up the tray, Yuzu sat back down, balancing it carefully on her lap. Considering the obvious lack of anything else for her to do in this place, she decided to savor the food. It would last longer that way. Carefully, she lifted a spoonful of the miso soup to her mouth, inhaling the smell. Partly to check to make sure it wasn't… off. Just in case.

But it wasn't, and it tasted normal, too.

She had just taken the first bite of the apple when something important occurred to her.

 _Only Hollows could open garganta_.

It was a stupid plan. An obvious plan. It would never work.

But… it played to her strengths. And it was so obvious that it might just be right under Aizen's nose. He clearly didn't think much of his subordinates—that was a mistake.

All Yuzu had to do… was make a friend.

* * *

 _Term Dictionary_ :

 _Bensakujo_ – 限削除 – "Limit Release/Restriction Cancellation." Hasuhime's special ability in shikai. Yuzu selects one parameter for an object, person, or ability, and cancels/raises the "limit" of that thing. So, for example, kidō are limited by their intrinsic shape—but by using Hasuhime, Yuzu can remove that limitation and reshape them in any way within her power. Used on a person, she can effectively increase one parameter of their abilities: speed, strength, a time limit, or something like that. The degree of change is bounded by Yuzu's own power (so she can't just make someone infinitely strong or anything ridiculous like that), and the applications by her knowledge and creativity. She can also only release one "limit" at a time—switching to a new one requires replacing the limit of whatever she is currently releasing. It's basically a really strong "buff" ability, in gaming terminology, with a reality-bending flavor.

* * *

It occurs to me that Gin's accent (and to a lesser extent, Shinji's) might be reading kind of weirdly to you if you've only seen the anime dub. In the manga, etc., both of those characters speak with the Kyoto-region dialect called Kansai-ben. It's fast-paced and slangy compared to other dialects, and for that reason, it usually gets translated (in American English) as a "southern" accent. Hence lots of missing word-ends and some extra a's and r's. So… that's why they're written like that here—Gin more markedly than Shinji, because he totally plays it up on purpose, the troll.

Kenpachi and Renji also drop word ends and run stuff together, but that's just because their way of speaking is rougher; they grew up in places where education was not readily available. Renji tries to adapt a little bit—Kenpachi doesn't bother.

That was all probably super-obvious to you guys anyway, but I figured I'd put it out there in case anyone had only watched the dub and was like "why is Gin talking like that?" He has such a weird lofty voice in the English-language anime and this is way different. :)


	7. Chapter Seven: Rivers Overflowing

_._

* * *

 _Catastrophe Theory_

A Bleach Fanfic

Chaos Theory AU

Chapter Seven: Rivers Overflowing

* * *

It was three days after the Espada's attack that Yoruichi sensed a familiar presence approaching the shop.

Shinji had been… _around_ , to some degree, but he rarely elected to interact with any of the others, and if he brought anyone else with him, it was Rose or Hachi—they were least likely to cause friction, she supposed. But this presence belonged to none of the Visored.

"Yoruichi, when are we going to start training?" Karin spoke with her head in the fridge, rummaging around for something to eat. Presumably, anyway.

"Soon." She would have said tomorrow, but that might honestly depend on what her guest wanted. "Stay here for a sec, would you?"

So obviously, Karin followed her when she stepped out of the front of the store. They stayed under the front awning—a recent addition she'd had Tessai put in. She really didn't like being wet, and the rain was coming down pretty hard out there.

"I see you're still running a halfway house for degenerates." The apathetic tone of voice was pretty normal for him. He lifted the edge of his umbrella slightly to better make eye contact. For a moment, he glanced at Karin; but then he blinked, and he was looking at her again.

"Yoruichi? Who the hell is this guy and why does he look a lot like Uryū?"

She sighed. "Karin Kurosaki, meet Ryūken Ishida."

"Charmed," Ryūken deadpanned.

Yoruichi didn't miss the flicker of recognition at the name _Kurosaki_ , though; that made sense. She hadn't really been involved in that whole mess, but Kisuke had told her the story.

"You're his _dad_? I'd kick your ass if I didn't think he'd rather do it himself." Karin crossed her arms over her chest. Clearly, she was aware of the… falling-out they'd had.

"Karin, you're not helping." Then again… while Yoruichi thought she understood where some of these familial problems stemmed from, she couldn't _completely_ disagree with Karin's sentiments. Regardless of your issues, kicking your own kid out of your house when he was just fourteen was pretty damn cold. "Something I can help you with, Ishida?"

"Yes, actually. You can retrieve that boy from the Soul Society. Your situation is clearly desperate, and no doubt his own incompetence is proving to be quite troublesome to him by now. Tell him he can come see me if he still cares about his precious Quincy pride." He didn't elaborate, instead faintly inclining his head and turning away, disappearing into the rain.

"And here I used to think _my_ old man was the worst," Karin muttered, glaring daggers after him.

Yoruichi shook her head. "Sometimes I think it must be a men thing, to never be able to just say what you really mean."

Karin looked like she was about to argue; a thoughtful look crossed her face. "Honestly? I'm pretty sure that's just a people thing. …At least most of them."

She snorted. "Yeah… probably."

* * *

"I yield."

Rukia pushed out a sigh as the dark blade moved away from her neck. She'd almost had him that time, but the second sword really made it hard to beat him in pure melee. The forms he used weren't really like anything people used with more traditional kendo; she was glad to have the chance to fight against something so strange so regularly.

It helped, of course, that he always fed her afterwards.

Almost as though he'd read her mind, Ishida brought his swords together to seal them and sheathed the wakizashi that resulted. "Hungry? I'm no Yuzu, but I did make lunch."

She smiled. "I guess I can live with that." Rukia would never admit it, but he was a much better cook than she'd ever be. Not that she'd really ever tried; she'd gone from not really eating on the regular to having everything prepared for her by other people, so there hadn't ever been a need.

They settled on the side of the ring, so that anyone who might wander by wanting to use it could do so. She didn't trouble herself too much with manners; accepting the extra pair of utensils he'd brought, she picked out the parts of the lunch she was most interested in eating. By the time she was done, the split was mostly even in terms of volume, but she had all the best parts and they both knew it.

Ishida rolled his eyes at her. "Isn't it supposed to be 'to the _victor_ go the spoils'?"

"I dunno," she replied nonchalantly, popping a piece of fish into her mouth. "Aren't _you_ supposed to be a gentleman?"

He grumbled something she didn't hear, but complained no further. Feeling a little bad, she gave him back the eel nigirizushi, since she knew it was his favorite. Funny, the things you learned about someone if you were friends with them long enough.

Like the fact that his thoughts were half elsewhere.

"You're worried about them, aren't you?"

Ishida didn't try to deny it, pushing his glasses up his nose and maintaining a conspicuous silence.

She tilted her head to the side, letting her chopsticks linger at her bottom lip for a moment. "You know, that's not a bad thing. I'd be more concerned if you _didn't_ want to be over there with them." Rukia did—and she knew the twins were basically family to him at this point. Just like Renji was practically family to her.

"It doesn't do any good to worry," he said, frowning down at his rice. "I'd rather just…"

"Do something?"

He nodded.

"Yeah," she said. "Me too. But that's one difference between being on your own and being part of an organization. The upside is… they're not alone, either. Hitsugaya-taichō and Zaraki-taichō are good at what they do; they won't let anything happen."

Ishida's brows furrowed—he didn't look convinced. "It's completely irrational, but… I just have a bad feeling about this."

Rukia chewed the thought over with her food, letting it process for a while. "We're not allowed any contact with the advance team, but… no one knows you can call the Urahara Shop, right? If you're not sure about things, maybe you should try contacting Yoruichi."

He pursed his lips. "I think… that's probably what I'll do. Thanks, Rukia-san."

"Glad I could help."

* * *

Yoruichi settled down in front of the living room table, rubbing at the back of her neck. Taking Kisuke's communication device out of her pocket, she set it on the wood surface. Really—her life would be so much easier right now if that idiot had taken one of these with him. If they would even work in Hell, that is.

Switching it on, she adjusted it to call Jūshirō's and sat back. While it connected, she folded her legs underneath her. Ryūken might have been terse about it, but he wouldn't waste their time, especially not with everything that was going on. So if he had something to say to Uryū—or something to teach him—it was probably worth his while to hear it or learn it.

With a flicker, Ukitake's face resolved on the screen. Yoruichi resisted the urge to frown; he looked a little more wan than usual. Clearly not one of his better days. But as usual, he offered her a mild smile as though nothing were the matter at all.

"Hello Yoruichi-san. You've caught me with Shunsui, actually."

Kyōraku leaned in from the left side, his hat taking up half the viewing area because of how close he was.

"Move back, you lunk," she said, a small twitch at the corner of her mouth. And that despite the gravity of the news she had to deliver.

Kyōraku complied, shifting around until he was simply sitting next to Ukitake instead of trying to fit in from the side. "That's mean, Yoruichi-san," he whined. Even _his_ fool-act didn't last long this time, however.

"Tōshirō-kun reported in to Yamamoto-sensei yesterday," Jūshirō said. "He told us about Iba-san just a few minutes ago… and about Kurosaki-kun."

Yoruichi nodded slowly. "I was going to check if you knew, but… this isn't actually about that, at least not completely."

Jūshirō blinked; Shunsui only cocked an eyebrow. He'd produced a cup of sake from somewhere. Probably the other side of the table or something. He'd never let something like social conventions about time of day stop him if he decided he wanted sake. Yoruichi was pretty sure he just didn't care that much about social conventions, period. It tended to happen, she supposed, if you lived that long.

Thinning her lips, she pressed out any traces of amusement. "Actually, I'm glad you're there, Shunsui. I need to ask a favor of you."

"Do you, now?" he said, affecting a blasé attitude. "Am I going to like this favor?"

She shrugged. "Maybe eventually. Probably not right now. I need you to assign your tenth seat to the living world advance team."

Technically, the plan had been to just… _remove_ Uryū, if the time came. But she wanted to try and do it in such a way that he could go back eventually. He was terrible at admitting things like this, but she was certain he actually _liked_ it there. Or at least liked some of the people. She didn't want to completely ruin the life he'd built for himself if she didn't have to.

"Ishida-kun?" Shunsui looked thoughtful. "Now you know I like to let the two of you over there do what you have to do without asking too many questions, but… I _am_ training him, you know. I put actual work in and everything. It'd be a real shame to lose him before it was done."

Yoruichi tilted her head from side to side. "I know; he's told me about it. And it's good that you have, but… his father wants to see him. It's about the Quincy."

For several moments, there was a heavy silence. Finally, Kyōraku gave a ponderous dip of the chin.

"Well… I guess that changes things a little, now doesn't it?"

* * *

Yuzu had discovered rather early on that there was nothing interesting about her room. It had white walls, a white floor, a white rug, a white sofa, and a couple bits of pale wood by way of tables and the like. The one window with two bars gave her an interrupted rectangle of sky to look at, but the angle didn't let her glimpse anything but a patch of blue and some bright light.

Within a day, it had bored her near to tears. She suspected that was intentional. She had _Jinzen_ , if she really needed to see something else, but she didn't want to risk the sensory deprivation. Not when she had no idea what would happen to her when.

Slowly placing one foot in front of the other, she paced back and forth over the rug. The hakama of her black shihakushō was a relief on the eyes, actually; she kept her gaze fixed on the way it contrasted the rug. A servant—or what she presumed must be the equivalent—had been by and brought her what looked like an Arrancar's uniform, but she knew better than to wear it. And since she had a few basic cleaning and sanitation kidō in her repertoire, she could wear it indefinitely and be comfortable and tidy enough.

Pausing in her motion, she considered the uniform. She'd folded it neatly and set it on the rug next to one of the couch arms, for lack of anywhere better. It _could_ have been an innocent gesture—it would be easy to assume she needed something else to wear, and then just basic manners to provide it. But she wasn't sure _innocent_ was a word that had ever applied to anything Aizen had done. This almost certainly wasn't.

Lifting one of her hands, Yuzu bit down lightly on her thumbnail. It was obvious what it was for—he was trying to make sure she looked like one of them. That could be for a lot of reasons; she went ahead and guessed it was for all of them. But there might be a way to take advantage of it, if she were creative enough.

She also still had her Fourth Division standard medical pack. Bandages, a salve, two rejuvenation pills, and a small vial of shinten. She'd need the whole thing just to knock out one person in this castle, she suspected—and that was if it worked at all. Still… she had it.

Since no one had searched her or anything, she also had a few things from Urahara's that she'd been carrying at the time she left. Mostly the things she'd wanted to take a closer look at later, but didn't actually know how to use. One of them, a small rubber ball, had been labeled 'gigai, inflatable' on the shelf. She wasn't sure what use that would be, but she figured it was better to have than not; it might come in handy eventually.

And then, of course, she had Hasuhime, though she wasn't permitted to draw her unless Aizen said so.

It wasn't much of an inventory, considering what she was up against, but it was more than she would have had if Aizen were taking her at all seriously. So… now she just had to find a way to put her plan into action.

She decided right there that if she was going to have a hope of actually making a friend, she was genuinely going to have to want to _be_ one. Yuzu didn't think she had an elaborate ruse in her—trying to manipulate someone into caring enough about her to get her out of this place just wasn't going to work. Not if she wasn't willing to put in the same care. She'd give it all away somehow—and it might just make her feel worse than anything Aizen could do to even try in the first place.

Which meant… she had to make a friend for _real_.

She thought she could do it; she'd made friends with some pretty reluctant people before. But—she had to choose carefully, and even that much involved actually _interacting_ with the Arrancar. The Espada, she decided. It had to be one of them, or else they might not be able to open a garganta anyway, and then both she _and_ her new friend would be stuck here and miserable.

Her first thought was the one who brought her food. He still hadn't told her his name; in fact, he hardly spoke to her at all. That would make things difficult—plus… she'd watched him hurt Iemura-san. It was difficult not to think about that. But she'd keep trying; maybe if she was persistent enough, he'd start to crack open a little.

She hadn't seen any of the others since that first meeting. So the first step was to get herself more opportunities to do so. Yuzu glanced around the room, but it offered up no clues. She'd been told to 'stay here' and keep quiet. Maybe…

Moving to the other end of the room, she hovered in the doorway, fingers curled over the frame. She'd tried to avoid the hall so far because she felt strange without a closing door. Now, the openness of the room might be her biggest asset. Stay here… but where, exactly, was _here_ supposed to be? Did they have someone watching her? What would it take for them to come out?

Rolling her lips together between her teeth, Yuzu popped them softly. She couldn't do anything too dangerous or suspicious. She didn't want to give herself away. But… hm.

Poking her head out into the hallway, she glanced down both ways. She wasn't at a dead end; maybe someone would happen to walk by. Lowering herself to the ground, she sat right in the doorway, angling herself to look down the left side of the hall and pressing her back against the opposite part of the doorframe.

Now, to wait.

* * *

"Ishida-kun. The captain would like to see you in the office."

Ise waited until he'd actually glanced up and made eye contact before nodding and stepping out of his doorway. He didn't envy the armload of paperwork she was carrying—maybe she'd actually gotten Kyōraku to _sign_ some of the captain's forms she filled out.

The fact that he was in the office and not on the roof or at the Thirteenth was surprising enough in and of itself.

Adding his own name to the bottom of his last piece of work, Uryū slid it into his outbox and stood, picking up his half-full cup of tea with his fingertips and standing. His shoulder twinged uncomfortably; he rubbed at the slowly-forming bruise there with his free hand. It was empirical evidence that he definitely hadn't forgotten to show up to sparring practice a few hours ago, so he had no idea what the captain wanted with him.

The Eighth in the afternoon was a lot livelier than the Eighth in the morning, to be sure. Uryū neatly sidestepped Third Seat Enjōji, who was walking backwards while talking to the new sixteenth seat. She, walking forwards like a normal person, caught his eyes and rolled hers. He could sympathize.

Kyōraku was indeed in the office, and surprisingly _not_ taking a nap on the floor. Instead, he'd tipped back partway on his chair, one toe planted on the ground for balance and leverage. He smiled amiably when Uryū paused to bow at the entrance—though he knew the captain didn't stand on ceremony, it was better not to forget the details.

"Ishida-kun. Come on in. Why don't you shut the door behind you?"

That, more than anything, tipped him off. Carefully, Uryū slid the door closed, standing in front of Kyōraku's desk, one hand at his side and the other still holding his teacup. "What's the problem?" It _had_ to be a problem.

His captain sighed. "I forget how bad you are at small talk sometimes. But I suppose it's for the best." He paused a moment; both front legs of the chair hit the floor softly. "Your friends are in a bit of a bind, Ishida-kun."

"Which ones?"

It occurred to him that this was not a question he'd ever thought he'd need to ask.

"The Kurosakis."

Uryū stiffened. Both of them were in the living world right now. Dread formed a tight, heavy knot at the pit of his stomach, like a ball of lead: dense and poisonous. "What's the problem?" he repeated, softer this time.

"Yuzu-chan's been kidnapped." Kyōraku watched him carefully.

"When?"

"Three days ago."

Uryū closed his eyes, swallowing his anger and fear. They could fester with the dread. "Why am I only finding out about this now?"

"Because I only found out about an hour ago," Kyōraku said slowly, tipping his hat back with one hand. There was something almost… dark, to the way he pronounced it. But it was vague, difficult to pin down.

The anger shifted focus to something further away, but Uryū's posture did not ease. "How do we get her back?"

The captain shook his head slightly. "The Sōtaichō probably won't authorize a rescue mission. Not for one shinigami. Until we have a way of opening a garganta, it wouldn't be possible anyway. But… something else has happened. I just finished talking to Yoruichi-san. She says your old man came by the shop. Apparently, he has something he wants to talk to you about."

A flash of irritation crossed Uryū's face. "I'm not interested in speaking to Ryūken," he said bluntly.

Kyōraku blinked at him. "I wasn't aware you had the luxury of choosing whether or not you wanted to get stronger, Ishida-kun." He paused; implication hung thickly in the air. "Isn't that what you want? To be strong enough to fight this war?"

Uryū's jaw tightened; he didn't want to disclose the secret, but… Kyōraku probably already knew anyway. "Nothing my father could say to me would help, anyway. I don't have Quincy powers anymore."

His captain didn't seem the least bit surprised by this. "I'm sure he knows that," he said evenly. "But he wanted to see you anyway. According to Yoruichi, the words were something like 'if you still care about your Quincy pride.' Seems important."

"So… what, then? I leave the Gotei 13?"

Kyōraku smiled at that, a glint entering his dark eyes. "I sure hope not. Nanao-chan would kill me if I let the division's second-hardest worker go over something silly like a war. No, Ishida-kun—I'm ordering you to go, as a member of the Eighth Division, and learn whatever you can."

Uryū knit his brows. "Does the Sōtaichō approve of this plan?"

That earned him a soft snort. "Are you kidding? One thing I learned really early on is that it's way easier to ask Yama-jii for forgiveness than permission. Don't worry about the old man; when the time comes, I'll handle him. He's already let me get away with treason anyway. How much worse can it be?" He waved his hand in a lazy motion.

"How am I getting out, then?"

"That one's easy: you can use my Senkaimon. Be back here in… oh, an hour. Jūshirō and I will get you to the right place."

* * *

"You know, there are better places to take a nap."

Yuzu—who _had_ been dozing, but not so deeply she hadn't noticed the approach of this much spiritual pressure—cracked her eyes open, tilting her chin to peer up at the Arrancar.

She recognized him from the throne room, more from the feel of his reiatsu than his appearance. It had been difficult not to look at Aizen. Now that she had the opportunity, though… this one was quite tall, and a bit on the thin side, for a warrior. Not that it meant anything, when reiryoku counted for so much more. He had sort-of-shaggy dark hair, and half-lidded eyes—she thought they might be a slate blue or grey.

She looked back into her room, and shrugged. "Not for me."

He blinked slowly. His facial expression, she thought, was pretty apathetic, but he didn't just leave. That was a good thing, right?

"Must be boring if you can't even sleep," he muttered, sliding his hands into his pockets.

Yuzu offered a half smile and the whole truth. "It will be, but right now I'm a little busy worrying about whether or not I'm going to die soon."

His eyebrows furrowed slightly; apparently that was not the answer he'd been expecting. He stayed still otherwise though—actually he was _very_ still, almost like some kind of statue. A monolith on the flat landscape of the hallway. "I wouldn't let it bother you too much," he said at length. "You wouldn't be here if there wasn't a reason. They went to a lot of trouble to make that happen."

She nodded. "I know. But when that's done, whatever it is… he won't just put me back, I don't think."

"Hm." He didn't seem to have much to say to that.

Yuzu's legs were starting to fall asleep from how long she'd been in the same spot on the floor. She drew the left one up a bit and tried rubbing a bit of life back into it. Keeping her eyes on her knee, she figured it couldn't hurt to try.

"Um… this might be a strange thing to ask, but… it's been three days since I was brought here, right?"

"Yeah; why?

She shook her head, switching legs and glancing up at him. "The sun never moves. Or, I should say, we never move in relation to the sun. It's difficult to keep track of time, is all."

After a couple of seconds, he nodded subtly. "It's not real. There's a canopy over Las Noches that simulates daytime sky. It's always night in Hueco Mundo."

Her eyes rounded. "You mean you never knew what the sun looked like before?" It was difficult for Yuzu to conceptualize an endless night; more than anything it sounded depressing. Even the people she knew who preferred night time would never want it to _always_ be like that.

"Still don't," he pointed out. "It's fake, remember? Though I guess most of us have been to the living world by now."

Something about the way he said that… "But not you?"

"No."

With the feeling returned to her legs, Yuzu pushed herself to her feet. She was still very, very short compared to the Arrancar. But at this angle, she could see his expression better. It still seemed mostly disinterested… but now she had to wonder about that. Why would he bother talking to her if he had no reason at all?

"Would you like to come in?" she asked, because really she had nothing to offer but somewhere different to hold the conversation.

He shook his head. "I have to go; I'm probably already late." He didn't seem particularly concerned about it, however.

"Oh." She felt a stab of genuine disappointment. Three days with so little company in a place like this had left her a little lonely, it seemed. "Well… if you ever feel like coming by again… it's not like I'll be anywhere else."

He considered that for a moment, then inclined his head. It was only when he turned to leave that she remembered something.

"Um."

He paused, glancing back over his shoulder.

"I'm Yuzu. Can I ask your name?"

"Starrk."

* * *

Uryū had almost managed to forget that Kyōraku-taichō was a member of one of the four noblest families in Soul Society.

Seeing the actual mansion involved, he knew he wouldn't forget again.

It was a sprawling edifice, sitting proudly—and perhaps more than a little ostentatiously—on a hill in the Seireitei. Though he was a poor judge of architecture compared to clothing or food, Uryū supposed the materials that had gone into its construction were exquisite. At least, the wood was a rich red-brown color, polished to a shine, and the stone was so smooth silk would slide across it. Once they got past the gate, the yards proved to be likewise immaculate. Uryū wondered how many people it took to keep them that way.

He gave his captain a sidelong glance. Kyōraku was intentionally incongruous to the setting. At least, Uryū had to assume it was intentional. He wore his shikakushō loose; his hat was plain and cheap—Ise said he bought them by the dozen—and the women's kimono he wore as a second haori was middling at best, in terms of both fabric and craftsmanship.

"Do you really live here?" He asked. It was a rather impertinent question, perhaps—but Kyōraku wasn't petty enough to take offense to something like that.

"Are you kidding? Live with my family? No thank you." He made an exaggerated face and shook his head.

Ukitake sighed. "They aren't that bad, Shunsui."

"Yes they are."

Ukitake compressed his lips. He looked like he might actually agree. "Shunsui owns a smaller house closer to the division, like I do."

The captain made a vague sound of agreement, leading them around the main house buildings towards the back of the grounds. "We should hurry before anyone notices I'm here."

"Why?" Uryū lengthened his stride to keep pace. He considered suggesting _shunpō_ , but they didn't have _that_ far to go. "Will they turn us in to the Sōtaichō or something?"

"Worse. They'll drag me into a meeting and start talking about _heirs_." Kyōraku shuddered.

Honestly… Uryū was pretty surprised about that on a few counts. He could believe that his captain didn't want to deal with having a family. For reasons of laziness at the very least. But cynically, he wondered if it was really possible that a serial womanizer who'd been alive for _at least_ several hundred years didn't already have children somewhere.

Then he considered the possibility that he _did_ , and nearly shuddered himself.

"I think I know what you just thought," Ukitake told him, tone oddly sympathetic.

"Hopefully I'll never think about it again," Uryū replied.

Kyōraku glanced back at them over his shoulder. "Why do I feel like you two are making fun of me?" he asked.

Of course, returning his thoughts to the matter at hand meant returning them to much darker places; Uryū grimaced and pushed a breath out of his nose. They passed by several members of what must have been the household staff; to a one, they seemed surprised to see Kyōraku. Pleasantly so, though. He returned the greetings offered with pleasantry of his own; his buoyant demeanor was the kind of thing that had a way of putting other people at ease, even when he was in a hurry and saying he couldn't stay long.

As the captain often observed himself—if in a roundabout way—it was a trait Uryū certainly did not share. The very _existence_ of that kind of charisma was vaguely mystifying to him, actually.

"Has he always been like that?" he asked Ukitake. They'd known each other most of their lives, apparently.

"Shunsui? Well… in a way. He's very perceptive, especially when it comes to people. He's never been the sort to take his station too seriously, which does him about as much good as bad, most of the time." Ukitake smiled. "I admit I'm a little biased, though—we ended up friends because of that quality in particular."

Finally, they reached the Senkaimon. It was smaller than the one the Gotei 13 used, and tucked away in a small outbuilding. Inside the building was nothing beyond a simple long room with a wooden floor. The gate itself was in the shape of a torii, down to the shimenawa strung from one side of it to the other.

Uryū remained a few steps back from the gate, while Ukitake and Kyōraku moved to either side of it. With a short incantation, they both channeled reiatsu into the structure itself, which activated with a soft humming sound.

"Ready, Ishida-kun?"

He nodded. He'd made a point of saying his goodbyes—few as they were—in person. If all went well… he'd come back.

"Until later, then. Good luck out there."

Uryū stepped through the Senkaimon, surprised when it actually put him out on ground level. Well… that confirmed his hypothesis that it was _possible_. He was actually quite close to the shop, too—only a few blocks away. He hopped into _shunpō_ , reading the reiatsu signatures along the way and frowning when he discovered the strange cluster of them on the other side of town. They felt bizarre, like they were shinigami but also… not.

He forgot all about it when he pulled to a stop in front of the store. He was immediately hit with a solid impact; a pair of thin arms curled around him. He didn't need to look down at the head of dark hair to know who it was.

She squeezed him tightly—Uryū found the wherewithal to hug her back, dropping his chin to the crown of her head.

"Uryū—she's gone." The words were muffled by his shihakushō.

He swallowed, tightening his hold. "I know, Karin." He pulled in a shaky breath.

"…I know."

* * *

 _Term Dictionary_ :

 _Torii_ – 鳥居 – Literally "Bird Perch." Your typical Shinto gate, usually painted red.

 _Shimenawa_ – 注連縄 – "Enclosing Rope." You know those ropes with the paper talismans on them that are sometimes hung from Shinto shrine gates or tied around trees, etc.? This is what that's called. Believed by Shinto practitioners to ward off evil spirits, or, if tied around an object, used to indicate the presence of a kami. The paper bits, called _shide_ (紙垂) "hanging paper" represent purity.

* * *

So Uryū makes his appearance at last; I think we all know what Ryūken wants to see him about. :)

That, more Yuzu and the Arrancar, and some training for other people as well up next. A plot device from canon will be making a late appearance in a different, yet familiar fashion as well.


	8. Chapter Eight: Voice of Rage and Ruin

_Content Warning:_ Unwanted physical contact with sexual overtones; verbal implications related to sexual assault. Relatively canon-typical on both counts.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Eight: The Voice of Rage and Ruin

* * *

"Hey. You."

"Hm?" Yuzu looked up from where she was methodically working through her food. Still no luck on her attendant's name, though she'd gotten him to actually speak to her today. It was really hard to tell if that was progress, or if he just considered it annoying.

But her visitor this time was Grimmjow. Odd, since she'd never expected he'd voluntarily bother with her. From what Starrk said, he was a bit of a loose cannon, with a penchant for fighting. That sounded familiar—but she knew she wasn't the kind of person who was interesting to that sort.

"If forgot I had something else I wanted you to fix." He spoke bluntly, but she thought maybe the hard edge to his tone was just habit. He didn't seem angry with her, anyway.

"What is it?"

He didn't look injured or anything, she thought.

Grimmjow turned around, pointing over his shoulder and down with his thumb. There, on the third quadrant of his back, was what looked like a burn scar. It was almost perfectly circular. Yuzu pressed her lips together.

"How did you get that?"

He glanced back at her. Yuzu could see from his profile that he was scowling openly. "After Tōsen cut off my arm, they picked a new Sexta Espada. Can't be two number sixes at once. So the asshole burned off the mark. I want it back."

Yuzu didn't know which person was 'the asshole'; she supposed Tōsen or the other Sexta were the likely candidates. It probably didn't matter. "Burn scars are difficult," she told him, "but I think I can help. Would you mind sitting on the back of the couch for me?"

Grimmjow shrugged, but balanced easily there. He pulled his legs up underneath him and crossed them, tipping his head back and fixing his eyes on the window. He was still frowning, but it had a different character than before.

Yuzu climbed onto the seat of the couch, slightly to his left, and rose onto her knees. Normally she would have had someone lay down for this, but she had a feeling that wouldn't have gone over so well as a suggestion. At least she could see the injury better now—the skin was pink and shiny, rougher than everything surrounding it. It was also old enough that she'd really have trouble getting rid of it, but she thought she could do it.

Fortunately, Aizen had never actually forbidden her from using kidō. The descarification kaidō was pale green; she channeled it through both hands. "The one that replaced you… was it Luppi?"

He scoffed. "Was."

Well… that explained _that_. Yuzu moved her hands to hover over the old burn, working the reiatsu into Grimmjow's skin. "Let me know if I'm hurting you."

He shook his head. "Nah. I don't hurt easy." He shifted a little in his seat—she wasn't sure he was quite able to just be still. He had a sort of restless energy to him. Completely the opposite of Starrk in that way.

Actually…

"Um… don't take this the wrong way, but… are you okay? You seem a little tense." Yuzu adjusted the flow of her reiatsu, healing the deep tissue first. She shifted on her knees.

He glanced back and down at her. "You try having a buncha souls crawlin' in your head all the time and see how relaxed _you_ are."

Yuzu's eyes rounded; the kaidō in her hands flickered, then steadied. "You can… you can hear all the souls you've eaten?"

"It ain't hearing." He was quiet for a while.

Yuzu fell silent, too. She thought that maybe if she didn't say anything, he might just keep going. Maybe he actually wanted to talk about it; maybe he couldn't stand the silence. Either way, she turned out to be right.

"You can when you're a Gillian. Then it's just fuckin' noise, all the damn time. Everybody in there is fightin' to be in charge of the body. Eventually someone wins, and the rest of 'em just kinda… fade out, yanno? Then you're an Adjuchas, and all you can think about is getting stronger so you don't go back and do it all over again with the next things you eat."

"But you still feel them? Even though you're an Arrancar?"

"What, you don't feel _your_ power?"

Yuzu supposed he had a point there. "Sorry," she said, though she wasn't sure exactly what she was apologizing for. "I just don't know much about you, is all."

Grimmjow grunted; she figured that was about as close to 'apology accepted' as she was going to get. Slowly, she eased away the burns, restoring the skin underneath to its former condition. The wound had been pretty superficial—probably because of that tough skin they all had. But the first few layers were burned off, so the tattoo appeared faded. She could pretty easily make out the shape of a stylized number '6', though.

"It's not quite what it was," she warned. "But you can see it."

Grimmjow hopped off the couch, running a hand over the newly-healed spot on his back. "Good." He turned halfway around and made eye contact. "That's two I owe you, kid."

Yuzu smiled, but she was taking a mental note of that. "It's no problem, Grimmjow-san."

* * *

Uryū had stayed at the Urahara Shop for the rest of the day and night after his arrival, but he'd left the following morning for his old man's place. Karin couldn't say she was happy to see him go—but at the same time, knowing he was in Karakura and training to help rescue Yuzu did a lot. After all, the three of them were damn good when they were working together.

Running the last bowl under the water, Karin handed it to Renji. He was on drying duty—since neither of them could cook worth shit, they had to do cleanup. She normally hated chores as much as anyone, but lately the mindless tasks like this had kept her pretty distracted.

"Hey, Karin-chan." Yoruichi appeared in the kitchen doorway, arms crossed. "When you finish up there, head down to the basement. There's something I want to show you."

"Sure." Turning the tap off with her elbow, Karin dried her hands and glanced at Renji. "Any idea what she wants?"

He shrugged. "Seems like you should go see."

The basement itself was basically a wreck; Renji and Kenpachi tended to spar down here, which always destroyed parts of the ring. Sometimes it got iced over, too, but at the moment it was just basic room temperature. No one else besides Yoruichi was around, which was pretty surprising.

"Over here." Yoruichi stood next to some kind of weird… dummy thing. It was totally white, and didn't really look that sturdy, even compared to some of the equipment in the Sixth. It had a generic person-shape, but no recognizable features otherwise.

"What gives with that thing?" Karin asked.

The other woman smiled. "This is one of Kisuke's more useful inventions. Let me ask you a question, Karin-chan: have you been training for bankai?"

"Bankai?" Of course she'd _thought_ about it. She did her _Jinzen_ every day, but she hadn't even gotten her shikai techniques down until a couple months ago. Those could still improve, too. "I mean… not really."

Yoruichi didn't look surprised. "Normally, if you got bankai at all, it would probably take you years. Even the really talented people who focus on it have to work for it—and a lot of it also depends on how willing your spirit is to cooperate." She paused, a slight smile curving her mouth. "This… lets you bypass all of that."

Karin goggled. "What?"

"It's a training aid. If you stab it with your zanpakutō, it will manifest the spirit, which lets you train for bankai. The downside is the danger—if you do this, you only have three days, and it will push you as far as you can possibly go. Only Kisuke's ever managed it before."

Three days.

She could have bankai in _three days_.

She could have it when they went to get Yuzu. Against the Arrancar.

Karin drew Hisaku. "All I gotta do is stab that thing?"

Yoruichi nodded.

"Fine. I guess Zaraki's gonna have to find something else to do for a few days." Karin leveled Hisaku in front of her, taking a deep breath. On the exhale, she ran the dummy through.

* * *

"Aizen-sama wishes to see you, girl."

Yuzu felt a tiny knot of apprehension tighten at the pit of her stomach. On the one hand, perhaps this meant she'd finally get some answers about her purpose here. On the other… any time she stepped into that man's presence, she was more likely to die than if she were out of his sight. She was sure of it.

Her fingers curled into her hakama; she shot the still-unworn Arrancar uniform a glance. It was impossible to tell what would be best. Maybe it wouldn't matter either way. Maybe he'd already seen through her intentions—she'd heard stories of how formidable he was, in intellect as well as strength. She was a mouse facing down a dragon; she knew that. Part of her _strategy_ was trying to remain beneath his notice.

But she was here because she'd already failed to do that, at least on some level. Standing, she dusted herself off, rolling her shoulders back and nodding to the green-eyed Espada. If Grimmjow was number six, she wondered which he was. It didn't seem like the kind of question he was likely to answer.

He led her out into the hallway—it was the first time she'd actually left the room since they put her in it. Though the corridors inside Las Noches were mostly featureless, her eyes drank them in all the same, because they were _different_ from where she'd been for the last four days.

"Am I allowed to know what this is about, or is it supposed to be a surprise?" She didn't expect her guide to answer; particularly not considering the touch of exasperation she couldn't quite keep from her tone on the last word.

"Even if I wanted to tell you, I don't know," he replied flatly—but it _was_ a reply.

Funny, how something that small could please her, when she might well be walking to the end of her usefulness. She suppressed the urge to smile, just a little.

Aizen's reiatsu was a constant, heavy pressure all over the place, but she could definitely feel it getting closer. It was oppressive to stand under—Yuzu knew that if he actually made effort to exert it, she probably wouldn't be able to keep her feet. She wondered if that was part of the reason everything felt so ponderous and dark here— _despite_ the bright light and emptiness of the castle itself.

She didn't recognize the room they went to, but she did take care to keep drack of the route they took together. All the hallways were empty and uniform in width; knowing where she was meant counting intersections and keeping track of which way they turned.

This room had a door. Her guide didn't bother to knock; he just laid a palm on one of the panels and pushed it open. It glided noiselessly on unseen hinges, admitting them into a chamber with a much more comfortable light level. Yuzu blinked; her pupils took several long seconds to adjust.

When they did, the image of Aizen resolved in front of her. He was standing in the middle of the room, next to what looked to be a cylinder anchored to the ground, about waist high on him and not that big across. The door was flanked by two female Arrancar; she hadn't seen them before. Personal attendants, maybe?

The man who'd led her here bowed low. Aizen inclined his head, and the Espada took several steps back, so he was behind her.

Uh-oh.

Aizen studied her for what seemed like a very long time. If she'd ever wondered what things in specimen jars felt like, she knew now. Yuzu bit the inside of her cheek, holding her spine straight.

"Leave us."

At first, Yuzu though he was talking to her—he _was_ making direct eye contact. But then she heard a sharp intake of breath from behind her and understood.

"B-but… leaving you alone with someone like this is…"

Aizen's reiatsu fluctuated. It was subtle, but Yuzu had gotten so used to what it felt like that she noticed immediately. So, apparently, did his guards. From the corner of her eye, she saw them drop, as one, to a knee each.

"Please excuse us!" They proclaimed in unison.

It didn't take a master strategist to guess how loyal they were. Yuzu flicked her eyes to her guide—he showed no reaction at all as they hurried past him. He simply folded his arms behind his back and remained where he was.

Uh-oh again, only worse. She wasn't sure if she was going to keep her _lunch_ much longer, much less her _life_.

"Now then. How nice of you to come and visit, Yuzu."

She immediately snapped her attention back to him. His reiatsu was back to normal, at least. She couldn't tell if that meant anything important. Goosebumps prickled along her skin, even under the warmth of her shihakushō. She swallowed.

Taking a leaf from his own book, she put a mild smile on her face. "It seems rude to decline an invitation," she said simply. If he wanted to act like she was here of her own will, well… she could play that game just fine.

"I'm sorry to call on you so suddenly," he continued—as though she hadn't been waiting around for four whole days. "But I have something I'd like to show you." Tilting his head down, he touched the pillar with a hand. Slowly, sections of it slid away, revealing a small compartment. Inside of it was a dark purplish object, swirling with inky-black undertones.

Yuzu sucked in a breath at the sudden change in the atmosphere. It was almost like that sphere had… reiatsu? But it wasn't quite like any reiatsu she'd ever felt. Even so…

"You feel it too, don't you?" Aizen's tone was soft, almost warm.

Suddenly, she understood how he'd fooled so many people for so long. She almost couldn't detect any malice in him at all. It was like he was… actually, the thing it reminded her of the most was the way a teacher spoke.

Her response was almost automatic. "Yes, it's… it's made of reiryoku, isn't it? Just—concentrated. Compressed."

"It is called the Hōgyoku." Fitting his fingers into the slot, he lifted it out for inspection. It seemed to have a transparent barrier of some kind around it. "Hundreds—no, thousands—of fragments of reiryoku, all combined in one object. A piece of god, wouldn't you say?"

Yuzu's lips thinned. To her it felt… static and heavy. Like someone had wrapped her in thick silk and bound her arms to her sides. Like nothing around it should be moving or changing, at all. Oppressive.

"It seems you understand," Aizen murmured. "Due to repeated momentary awakenings, it has deteriorated slightly, but it is definitely moving towards a complete awakening, don't you think?"

She didn't know how, but she felt that, too. Carefully, Yuzu inclined her head.

Aizen's mouth curled—he was perfectly aware of her nervousness, of course. "Making Arrancar from Hollows, creating an Ōken… without the Hōgyoku, I could achieve neither. Please think of my showing this to you as… a testament to my trust in you."

Yuzu's growing apprehension was stabbed through by a spike of skepticism. Trust? There was no way she believed that. This man… he wasn't the kind of person who trusted _anyone_ —much less an enemy. So why would he say something like that? Why continue this elaborate charade that she was some kind of guest here when the truth was obvious for anyone to see?

Her brows knit. "The damage it has taken… you want me to repair it."

"Not just yet. But in time, yes."

She licked her lips, taking in a deep breath. Nothing ventured, nothing gained, right? "Aizen-san… why are you doing this?"

He arched an eyebrow, but there was no immediate rebuke, nor fluctuation in his reiatsu.

"Not just _this_ ," she gestured between him, herself, and the Hōgyoku. She understood that part well enough. "I mean all of it. Why go to war with Soul Society?"

"Well, well… curious, aren't you?"

"A persistent personal failing of mine," she replied.

His eyes narrowed, but it didn't read as anger to her. "If so, then I suspect you already know why," Aizen said, replacing the Hōgyoku inside the slot. "That place… does everything it can to stifle brilliance and curiosity. To smother questions and thought. Surely you cannot tell me that you've never imagined a better world than that."

"You would go to war for the right to ask questions?"

"Wouldn't you?"

Yuzu swallowed. She'd walked right into that one. Aizen was studying her still, head tilted faintly to one side. Pulling her lower lip under her teeth, she bit down on it.

"Not like this," she said at last.

"No? Well, that's to be expected. You are young, Yuzu. You haven't yet seen right to the heart of the problem. When you do… I think you will understand why this is the path I have chosen." His eyes moved over her shoulder—he was looking at her guide now. Dismissal was clearly imminent.

She figured he was in a fairly good mood, if she was any judge at all—so it might be the best chance to get herself a little more freedom of movement. "Can I use the kitchen?" she blurted. "Cooking is my hobby. I swear I won't go through any door that's closed or anything, and I won't bother anyone."

Aizen blinked at her, then lifted one shoulder. "If you wish… clearly, confining you hasn't changed much."

Yuzu frowned. She had no idea if that was an observation or an admission, but in either case, she wasn't going to complain. "Thank you, Aizen-san."

* * *

"What the hell is this place?"

Uryū wasn't surprised by the existence of an underground training site. Those were pretty common in his life by this point. What _did_ surprise him was that Ryūken had built one under his hospital.

"It's exactly what it looks like," Ryūken replied. "A chamber made of reika silver and reika glass."

"Obviously," Uryū said, narrowing his eyes. "But that doesn't explain what it's doing here, under the hospital of a man who gave up his Quincy powers long ago."

"Hn. Is that what you think?"

The air shifted; Uryū felt the reishi particles in the air around him being pulled away. "It can't be…" he murmured.

"What I believe I said," continued Ryūken, drawing the particles towards his left hand. "Is that I have no interest." The reishi turned white, extending outwards into the shape of a bow. Ryūken raised it, adjusting his glasses with his free hand.

"…and you have no talent."

Uryū scowled. "If you just brought me here to gloat, Ryūken…"

Without warning or even a drawing motion, Ryūken fired an arrow. Automatically, Uryū stepped into _shunpō_ ; air rushed past his face as he launched himself to land to Ryūken's left.

"Calling your father by his first name… you really are a terrible son."

"So it seems." Uryū grit his teeth. "Wonder how I wound up this way?"

Another arrow flew in his direction, splitting into three. They were fast—even with flash steps, the third one grazed his sleeve, splitting the kosode of the shihakushō.

"Draw that sword and show me what the shinigami have taught you." Every syllable of the word _shinigami_ was infused with obvious disdain.

"Why?" Uryū didn't understand. "What's the point of this? You had me dragged out of Soul Society because of something to do with the Quincy. I can't believe this is all you wanted." He supposed it was quite likely that Ryūken disapproved of his choice to seek training in Soul Society; but Ryūken disapproved of _everything_ he did. It was difficult to believe he'd suddenly switch from completely ignoring Uryū's existence to… whatever this was.

"Because," Ryūken said, "if I wish it, your Quincy powers will return to you… provided you can survive the process, that is. Now… draw your sword, and come at me with everything you have."

* * *

If she were less aware of the gravity of her own situation, kitchen privileges might have set Yuzu at ease. She was glad to have them in any case—if nothing else, it was new scenery and an opportunity to do something with her hands. That seemed particularly necessary after her conversation with Aizen earlier; and that wasn't even counting the bizarre encounter in the hallway on her way here.

The Arrancar with the horned helmet and covered face really gave her the creeps. He'd appeared out of practically nowhere—she'd been looking down at her feet and then looked up. He hadn't been there just a moment before, but there he'd stood. He hadn't so much as moved until she'd passed him, hadn't responded to her confused greeting. But she'd sensed his eyes on her back until he turned the next corner. There was something chilling about his mere presence—he gave her a similar predatory feeling to the one Aizen did, except there was no veneer of politeness over it.

At least he hadn't followed her. The kitchen was as spare as the rest of the place in terms of aesthetic, but it was fully-equipped. That was actually kind of strange when she thought about it. Didn't Hollows subsist on souls? Why would they need a kitchen? Where did the food they made her come from? Maybe Aizen and the other ex-shinigami still ate regular meals?

Whether they did or not, the cabinets were well-stocked. She figured she could probably use whatever she wanted. It was weird to think it, but—while she expected he would kill her eventually—she couldn't see Aizen being petty enough to get upset over someone accidentally using his favorite tea or something. Did would-be gods _have_ favorite teas? Surely they must.

It didn't take her long to decide on onigiri—there were bunch of different things she could fill them with, and she was more interested in the task of cooking than in eating per se. So it seemed like a good choice. It took her a few minutes to figure out where everything was, but then she was pottering around in the place like it was any other kitchen.

"My, my. Who let you out of your cage, little mouse?"

Yuzu stiffened, carefully setting down the rice in her hands and turning around. It was neither a voice nor a reiatsu she recognized; the tone of it was completely unlike that belonging to the other Arrancar she'd spoken to.

The speaker was exceptionally tall—probably more than seven feet. He had a thin face and a white eyepatch on the left side. None of that was, in itself, particularly alarming. What _did_ worry her was the expression on his face. She'd seen people enjoy battle before—bloodthirst was not that unusual in the Gotei 13. But this was something other than that. A subtler, deeper kind of menace. His smile was too wide over his face, his eyes too narrow. It made him look a little like a weasel, in the worst way.

"Aizen-san did," she replied, hoping that invoking the name would be some protection here. Because she had the sense that she might need it. Her skin crawled; her instincts screamed at her to _get away._

He wavered and disappeared. Yuzu blinked, pulling in a sharp gasp when she opened her eyes. He was standing right in front of her. His hand snapped up, catching hold of her jaw in a tight grip. His fingernails dug crescent furrows into the skin of her cheek.

"Did he now? How unusual—it's not wise to let a pet run wild. Who knows what might happen to it?" His fingers tightened; they'd leave bruises if he didn't break her mandible outright.

She gritted her teeth, speaking through them. " _Bakudō #39: Enkōsen_."

He withdrew his hand as the shield stretched between them. Pale yellow tinged pink, and in the usual disc form, since she couldn't release her zanpakutō. He seemed more surprised than threatened; his expression quickly morphed to outright irritation.

"Why, you—let's see how well you cast your spells without a tongue!" He drew back his arm, landing a heavy blow on the shield that nearly cracked it clean through.

Yuzu took a half-step back. There was surely no way she could fight this man, especially not without Hasuhime's help. She might have to risk it, but—

"Nnoitra."

Both of them looked to the door. Her guide was staring flatly at the scene, but it didn't take him long to move his attention fully to his fellow Arrancar.

"Aizen-sama has explicitly stated that the girl is not to be killed."

Nnoitra sneered. "I wasn't going to kill a weak thing like her. Just teach her a lesson in obedience. Really, it's your own fault. You've clearly been remiss in taming her."

"I'm _not_ an animal." Yuzu regretted the quiet words almost as soon as she said them. They were true, of course; under any other circumstances, she would happily have said them. But these people held her life in their hands—turning any of them against her was something she could ill afford to do.

The Arrancar looked at her with a venomous sneer. "Don't go getting a big head, girl. You're here until your use is spent, and then you're dead. Perhaps Aizen-sama will allow me to kill you. I promise, I'll catch you up on your _lessons_ first."

"Degenerate scum. Get out." There wasn't really any _feeling_ in the words, but at least they'd been said.

Nnoitra's lip curled, but he left anyway, muttering under his breath. As soon as he was gone, Yuzu released a long sigh, letting her nearly-broken kidō flicker out of existence. Slowly, she allowed herself to relax a little, but it was surprisingly difficult.

She went to run a hand through her hair; just before she did, she realized it still had sticky rice on it and dropped it back to her side. "Thank you," she said, giving her guide a shaky smile. The whole thing had been rather jarring, but she had a feeling it could have been a _lot_ worse.

"I didn't do it for you," he replied. "Aizen-sama's orders—"

"—were that I not be killed," she finished, setting her hands on her hips. "Which means you didn't have to interfere, but you did. So, whether it was for me or not, I'm thanking you. The least you could do would be to accept it."

He blinked at her, very slowly. Yuzu heaved another sigh. So much for getting a response; it was like talking to a stone wall most of the time—

"Ulquiorra," he said.

"Huh?"

"You keep asking me for my name. It is Ulquiorra Cifer."

She beamed at him. It wasn't _rapid_ progress, but it was _something_. "Well then, thank you Ulquiorra-san." She let her hands fall from her sides and glanced back over her shoulder. So far, she'd only finished three onigiri; there was a lot more rice left over. "Do you want something to eat? I've gone and made far too much for just me."

"I am not hungry."

Despite herself, her smile faded. "Oh. Well, all right then. I'll just finish the rest of these anyway." She turned her back to him, quite certain that he wouldn't just decide to stab her for no reason, and picked up the rice ball she'd been working on before Nnoitra's interruption.

"Why did you resist him?" Ulquiorra asked.

Yuzu turned around and put her back to the counter, still shaping the rice in her hands. She'd salted her palms before she started, but it was still a hopelessly-sticky affair. But she liked the warm feeling of the cooked grains, and the simple, clean smell of them. It was a reminder of home—and compared to the emptiness here, an utterly revelatory sensory experience.

"What do you mean? Why did I use kidō, or why did I talk back to him?"

"Yes."

She huffed a short laugh. Apparently both then. "Um… well, I suppose I used the kidō because I thought he was going to hurt me, and I didn't want to get hurt."

He nodded slightly—apparently that made sense to him. She wasn't quite sure how she'd have been able to explain if it _didn't._ It seemed like the most basic instinct of all to Yuzu. The desire to protect oneself. To avoid pain when possible.

"As for the other part, I… hm." That was a bit trickier. From the few things he'd ever actually _said_ to her, she figured Ulquiorra was the kind of person who favored logic over emotion. He acted like he didn't even have feelings, but that just seemed impossible. He had to feel _something_ , even if it was very little.

Yuzu tipped her head back to look at the ceiling. "It's kind of hard to explain. I'd say… I did it because I couldn't stand the idea of being thought of as an object. I said animal, but really that would be a terrible way to treat an animal, too. I have my own will, even if it's difficult to act on it right now, you know. I still have feelings; I still have a heart—being treated like that… it felt like he was trying to take all that away from me."

She set down the rice ball, scooping another clump out of the pot and starting to shape it as well. "Does that make sense?"

"Not really," he said, expression unchanging. "Only humans and shinigami speak of things like hearts. It seems unlikely to me that they exist."

She frowned thoughtfully. Obviously he wasn't talking about the literal bodily organ—she hadn't been either. "Well… it probably doesn't help that everyone means something slightly different by it. It's not a scientific concept—it's a metaphor. For… our feelings. Our bonds with each other. Connections, things like that."

He still looked skeptical. Or, well… perhaps it was more accurate to say that he gave no indication that he understood. Yuzu picked up a small sheet of nori and wrapped it carefully around the bottom of the triangular onigiri. "Have you ever…" she paused, parsing her thoughts carefully before she spoke. It would be for nothing if he wrote her words off as complete nonsense. "Have you ever encountered anything that made you feel… different? From a normal state I mean. Anything that made you happy, or sad, or satisfied, maybe?"

She made it through three more onigiri before he responded. "Once," he said. "I wandered Hueco Mundo. I felt nothing for other Hollows—they were different from me, and I was different from them. There were no… connections… to be had. But I was satisfied once. I found a tree. It was white on the outside, and empty on the inside, as I was. I dwelled in it, for a while."

To her, that just sounded incredibly sad, but Yuzu didn't say as much. "There must have been a reason you were drawn to it, then," she pointed out. "And that feeling doesn't come from nowhere. After all, being white and empty might be… factual similarities, but acknowledging factual similarity isn't the same as being satisfied by something. That feeling—any feeling—comes from what we humans and shinigami mean when we say 'the heart.'"

He didn't concede, but he didn't try to argue the point with her, either.

She supposed that was something, at least.

* * *

 _Term Dictionary_ :

 _Reika_ –霊化 – "Soul-Synthesized." Reika materials, such as silver and glass, are made of especially densely-compressed reishi, in a forging process developed by Quincy, who can manipulate the energy into the necessary form.

* * *

So this update was slightly slower; to be honest, it's because I'm watching a ton of Olympics coverage. I don't even usually like sports, but I absolutely love the Olympics. It's pretty distracting, but I'll do my best to keep writing decently-fast. My goal is to finish this fic before I have to go back to school.


	9. Chapter Nine: Get Your Things Together

.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Nine: Get Your Things Together

* * *

Twenty-four hours into bankai training, Karin already felt like she was on her last legs.

She groaned as she lifted her sword to block another rapid series of strikes from Hisaku. Metal clanged on metal—the blades they used were twins of one another. Karin got the worst of it, staggering backwards three quick steps and only just managing to keep her feet. Breath sawed in and out of her lungs, but she kept going, using reiatsu to boost her motion with _Tobase_ and get out of the way of the follow-up.

She'd been expecting Hisaku to manifest as, well, a bird. That was what she was in Karin's inner world, after all. But—maybe because of the dummy thing, maybe because she needed arms to hold a sword—she was actually sort of humanoid. Her arms and legs both resembled bird feet still—they were yellow, scaly, and ended in hooked talons. She wore a complicated feathered headdress thing with a cranelike beak pointing out from her forehead and a bunch of red and gold feathers trailing down the other side. Her wings, constantly shedding embers, had moved to her back, and her tail dragged slightly on the floor.

Her face was human though—painted in red, black and white. Heavy gold bands of jewelry circled her biceps and wrists, clanging softly on her ankles as well. She was covered in a mix of loose clothing and feathers—Karin could say with confidence that the second worked fine for armor, too.

"Have you learned nothing?" Hisaku—not winded in the slightest—frowned at her. "What is this, but one more effort to break through a wall you've set for yourself? Bankai in three days? There are no true shortcuts to power, Karin."

"Yeah?" Karin bit back, gulping in another breath. "Normally, that'd be fine. But I'm gonna be honest here: I don't care about your damn rules right now."

She flew forward, taking the offensive this time. Hisaku met her first strike with an almost lazy flick of her sword, parrying it hard to the left. Karin tried to resist the force, but felt her stance opening right up anyway. The spirit punished her for it with a hard fist to the stomach, pushing her backward ten feet and into an ungainly sprawl.

Karin coughed; her lungs burned. The one fortunate thing about the match was that Hisaku didn't seem to want to kill her or anything; mostly, she'd just hit her bluntly every time she could have stabbed or cut. It still hurt a lot—and worse, Karin wondered if it meant that the spirit wasn't taking things seriously enough.

That seemed like the kind of thing Karin had to _make_ happen if this was going to work. Climbing to her feet, she activated _Sakebe_ , setting the blade of her katana on fire.

She had two more days; she'd better make them count.

* * *

Yuzu had started to notice a change in the rhythm of her captivity. It was pretty subtle at first; little to remark upon. She wandered the halls a lot more, so perhaps it was expected that she tended to nearly trip over a napping Starrk every time. Sometimes he woke up when she was nearby; sometimes he didn't. Sometimes they talked; sometimes they didn't. But he never treated her badly, and she never questioned his presence.

She occasionally caught flickers of Ulquiorra's reiatsu when she turned a corner or entered a new part of Las Noches. She knew he'd been assigned to make sure she was kept alive—doubtless her new mobility made such a task more difficult. Only rarely did she catch a glimpse of him, but for the most part, she didn't remark on that, either.

Every once in a while, her heart would skitter—when she felt Nnoitra closer to where she was than she'd expected. But whether due to the presence of her invisible shadow or something else, he hadn't directly confronted her since the first time. Aizen left her alone; the one time she passed Ichimaru in a hallway, he smiled a Cheshire grin at her but said nothing. She had no way of knowing what, if anything, _that_ meant. She tried not to let it bother her. So much of this situation was out of her control—she had to focus on what she could change.

Tier Harribel, the sole female Espada, and her all-female fracción, were interesting. The three subordinates had a distinct and obvious rivalry that Harribel herself seemed to ignore. She seemed kind of… spacey, to Yuzu, like her thoughts were always somewhere else. The one time Yuzu had attempted conversation, she felt stonewalled even more than she did when she spoke to Ulquiorra.

Harribel was a woman with depth, of that Yuzu was certain. She was _equally_ certain that there was no way for her to even begin to see into that depth.

Grimmjow, without a fracción anymore, wandered around even more than she did, prowling the hallways with that same restless unease she'd detected when he asked her to heal his back. He didn't seem to like Ulquiorra much, but he was… nice to her, at least by comparison. Which was mostly to say he nodded when they passed each other, usually kind of listened if she said something, and didn't growl or snap at her the way he seemed to with almost everyone else.

Then again, everyone else might be a threat or a potential fight. Yuzu was deliberately _neither_.

She'd pried the names of the others out of Starrk—outside of Nnoitra, the one who disturbed her the most was called Anzparrejar. She didn't know what number he was, but apparently he was an Espada. Starrk had looked at her strangely when she asked, and told her to avoid him. Thus far, she'd taken the advice.

"You're thinking too loud."

Yuzu blinked, turning towards where Starrk was; he'd reclined in a patch of sunlight falling in through one of the high windows in this living room. At least that's what she thought it was—it had the right sort of furniture, anyway.

"Oh," she said. "Sorry."

With a grunt, he pulled himself up into a sitting position; absently, he tangled his fingers in his hair and scratched his head, moving down to rub at his neck.

"How did it rate?" she asked, referring to the nap.

He frowned slightly. "Barely a four."

"Doesn't sound very restful."

"It wasn't. Never is, when I get pulled into the inner world." He yawned, bringing his feet up underneath him. His palms hit the floor; he reclined back on them.

Yuzu smiled sympathetically. "I didn't know that happened to Arrancar, too. I suppose it makes sense. You _do_ have zanpakutō, after all."

He pushed out a low sigh. "Yeah. It's not quite the same, but… I guess it's probably close."

"What's your zanpakutō's name?" She asked. The details of this were intriguing; she doubted the information would have much practical use, but she wanted to know anyway.

He blinked. "The formal one, or what I call her?"

"You… nicknamed your zanpakutō?" Yuzu had never heard of anyone doing that, though she supposed it was completely possible.

"Yeah. Well, her actual name is La Loba, but you can see why I wouldn't wanna bother with that if I don't have to. So… most of the time, she's just Lilynette."

 _Lilynette_ wasn't any simpler a name, Yuzu thought, but she supposed it was less… lofty. "What's she like?"

Starrk snorted. "She's a mouthy twerp who doesn't know when to be quiet and let me sleep." He frowned immediately after saying it—Yuzu had the feeling Lilynette wasn't happy with the assessment.

"Sometimes our spirits don't seem to be very much like us, do they?" Yuzu mused. Hers was, after all, a princess in a garden. With a castle attached.

"Maybe not on the surface," Starrk replied. "But I think deep down they are."

"I suppose."

"What? You don't believe I'm a bratty little girl on the inside?"

It was the deadpan delivery that did it. Yuzu burst into laugher, wrapping her arms around her sides. Her shoulders shook with the force of it. When she regained her breath, she was still smiling. Starrk wasn't, but she thought she _might_ have detected a faint flicker of amusement in his eyes. It faded quickly.

"I don't think I've ever heard that before." The words were quiet, thoughtful.

Yuzu tilted her head, raising her knees to her chest. "Heard what?"

"Laughter. Or maybe I should say… laughter that doesn't have anything to do with madness or bloodthirst."

"I wouldn't be so sure," Yuzu replied, equally soft. "I may just be going mad myself."

Starrk shook his head slightly. "I don't think I've met anyone saner than you," he said, matter-of-fact as ever. "It's your situation that's crazy."

Yuzu leaned forward, propping her chin between her knees. "Would you think I'm rude if I said you needed to get out more?"

He scoffed softly. Maybe—yes, there it was. One side of his mouth tilted, just a little bit upwards. "A little. But that doesn't make you wrong." His eyes wandered to the ceiling. "I tried to, once." He exhaled heavily, all trace of good mood vanishing with the sound. "But everyone that came near me just… died. I didn't understand at first, but it was my reiatsu."

Other Hollows had _died_ just from his reiatsu pressure alone?

"It doesn't feel so bad now," she ventured gently.

"It's easier to control. Lilynette helps. So does being an Arrancar. And also… you are stronger than they were."

Yuzu nodded slowly. "I'm sorry," she said. "That sounds really lonely." She couldn't really imagine it—being absolutely alone in the world. She didn't _want_ to. But she tried, for the sake of trying to understand what he was telling her. And maybe recent experience was giving her the first glimmers of the idea.

"It was," he replied simply.

* * *

There was something extremely uncanny about fending off a Seele Schneider with a zanpakutō. Uryū had only ever been on the other side of the opposition, and even after undergoing shinigami training, had _never_ expected that he'd be on this one.

Viewed from his current perspective, the cornerstone ability of the Quincy was formidable. He'd always known that, of course, but it was another thing to _feel_ it—to sense the humming edge of Ryūken's blade threatening to break down the material bonds that held Yorugen together. To watch his kidō burst apart before they even made contact. To try and outrun _hirenkyaku_ with _shunpō_ and _know_ that he wasn't fast enough.

To understand that, while he lived or died by his reiryoku alone, the amount of energy that Ryūken had access to was theoretically unlimited.

In practice, of course, it was different—how much his opponent could throw at him depended on how good at absorbing and converting the reishi he was. But there was no internal reservoir that Ryūken had to worry about emptying, unlike Uryū. For the first time, he thought he understood on some level _why_ the Quincy were bogeymen in Soul Society. Why his classmates at Shin'ō had reviled him the way they did.

They were afraid because this was fearsome.

Uryū quickly swapped places with his shadow, breath hissing out between his teeth when a cluster of arrows flew through what appeared to be his physical body. He switched back almost immediately—if he lingered too long, Ryūken would no doubt figure out the ability.

Ryūken closed to melee range, swinging one of the Seele Schneider like the sword it could be. Uryū flashed away, but not quickly enough—a bloody cut opened up on his shoulder. Ryūken was both extremely fast and extremely precise.

" _Kagegaitō_ ," he murmured.

His shadow, stretched at an angle in the stark light of the underground room, doubled. One of them rose up, forming into a dark mantle that settled without weight over Uryū's shoulders. He stepped into shunpō again, fast enough to leave an afterimage. When he appeared behind Ryūken, he took him by surprise. His back was wide open.

Uryū moved his arm back to strike… and hesitated.

The extra second was enough for Ryūken to realize where he'd gone. Turning, he blocked the incoming hit with his bow, knocking one of Uryū's swords to the side with a clang. The Schneider in Ryūken's other hand left a thin slash diagonally across Uryū's chest; he'd jumped away, but not fast enough to avoid the hit all together.

Ryūken didn't let up, pressing him with _hirenkyaku_. Uryū fought him off with one sword and a free hand, charging up a _shakkahō._ The Quincy blade sliced effortlessly through the kidō; Uryū used the smoke to disappear again.

Rather than attack Ryūken, he used the extra seconds to call Yorugen's second blade back to his hands. Hooking them together at the ends, he swung one forward with the other, slicing off a few white hairs with the sharpened handguard on the far blade. Whipping it back, he caught it again, knocking several arrows out of the air with the curve at the end.

"If this is everything you have, then there was no point in bringing you here," Ryūken said, firing another dozen arrows without a motion. Uryū jumped back, planting himself on the wall behind him and running to stay ahead of the stream of projectiles. They crashed into the reika silver and glass with sounds like small detonations—more like white lances than arrows, given their size.

Uryū gritted his teeth. At this rate, he was going to run out of energy first, even if neither one of them managed to incapacitate the other via injury. He still had a few tricks up his sleeve—but he wondered if he had the follow-through to actually use them.

* * *

Rangiku huffed an exhausted sigh, flopping down next to where her captain sat at the top of the stairs. From their angle, she could just see Karin still hard at work training against her spirit. Rangiku didn't really understand how this training method worked, but supposedly if Karin had the guts and the strength for it, she could get bankai in another day and a half.

Tōshirō had narrow eyes and a frown on his face—this particular look meant he wasn't quite sure how he felt about something. Probably about the fact that he was watching a teammate get beat up for something neither of them had ever even heard of, she guessed. Rangiku had to admit she wasn't sure of it, either; but Yoruichi knew what she was doing, and if anyone had the moxie to pull this off, it was Karin.

It probably proved her point when Isshin's daughter used her sword to burn closed the bleeding wound on her abdomen, pressing it to her skin like a brand. Rangiku swore she could hear the sizzle. She flinched. "She's still at it, huh?"

Tōshirō's brows knitted. He shook his head, like he was trying to get rid of some thought he'd had. "Halfway through."

"You've been here the whole time, haven't you?" Rangiku gave her tone a teasing lilt. She knew he'd read too much into it. That was the fun part.

He scowled at her. "I have not."

Rangiku smiled the cat's own grin; her captain _tsk_ ed. She knew he worried about how his subordinates were doing more than he'd ever let on. And even if Karin wasn't a member of the Tenth, they were teammates for this mission, and that counted.

"How's kidō training going?"

She sighed. "It's going. For such a quiet guy, Tessai's awfully demanding. He made me try _raikōhō_ without incantation today."

"Did you do it?"

Rangiku's mouth pulled sideways. "Kind of. I think he decided first-aid kaidō might be a better idea, though." She thought so, too. Rangiku knew she wasn't really good enough at any one thing to pick up the skills that the _really_ strong people could do. But she didn't have any major weaknesses, either, so she thought it pretty much balanced out in the end.

They were quiet for a while, watching the two combatants leap around the basement. Karin looked like she was barely holding on; by contrast, Hisaku had hardly broken a sweat.

"What happens if she fails?" Rangiku wondered aloud.

Tōshirō blinked. "She won't."

Her eyebrows went up. That was quite a strong vote of confidence. "How do you know?"

"It's her sister's life."

Rangiku wondered about that. Then again, she supposed if anyone would know, it would be Tōshirō. His mood lifted and fell more based on how Momo was doing than because of anything that happened to him. It was the same kind bond; he'd told her as much. She couldn't say she knew much about family, herself—other than the Tenth, the only person she'd ever really called family was… her thoughts jumped off that track skittishly.

"You think anyone's told Isshin yet?"

He shook his head slowly. "No. The Seireitei wouldn't; they don't even know where he is. I don't know if Shihōin could or not, but even if she has, it's not like there's much he can do right now."

"And we're not there to do it ourselves." Rangiku leaned forward, putting her chin in her hands and her elbows on her knees. Karin was throwing fire now; with the speed she was going, she was going to get tired pretty fast. Then again… she'd been at this for a day and a half, and she hadn't stopped yet.

Maybe the captain was right after all. Maybe it really was just as simple as _needing_ to succeed, for someone else's sake.

What a wonderful kind of love that must be.

* * *

Yuzu had managed to put a lot of information together by this point. She knew the names of the Espada. While Grimmjow's was the only number she knew for sure, she figured she had at least some clues, based on who she'd observed obeying whom. Ulquiorra had to be ranked higher than Nnoitra—she could think of no other reason Nnoitra had just walked out of the kitchen without a fight the other day.

Grimmjow's resentment towards Ulquiorra read to her like a one-sided rivalry, and she knew the former wasn't interested in people he thought of as much weaker than him; that placed Ulquiorra above six. Starrk had explicitly warned her away from Anzparrejar, so Yuzu supposed the latter might be near the top; anything beyond that was pure speculation.

She'd also learned a lot about their zanpakutō—namely, that they weren't that different from shinigami zanpakutō at all. Which meant some of the same principles should apply. Which in turn meant… she might have some good news for Grimmjow, and an inroad for herself.

His reiatsu signature was easily recognizable by this point; it was a live wire, sparking and stuttering, compared to the much more subdued and controlled signatures belonging to Harribel or Ulquiorra. Or the almost-nonexistent one Starrk allowed himself to project.

There was a closed door between Yuzu and where she wanted to go.

He was just on the other side of it, though—so if she approached this right, it might not stay closed. Grimmjow, she was pretty sure, appreciated directness and confidence. So Yuzu decided to be direct, and hope that the confidence thing wasn't a hard and fast requirement.

Raising her hand, she rapped sharply three times. He was awake, she knew that much.

"Fuck off," she heard from behind the door.

Yuzu frowned. "I'm actually not sure what that entails," she called back in response.

It took a few seconds, but the door opened inwards. Grimmjow frowned down at her. "What the hell are you doin' here?"

Well… at least he apparently hadn't known it was her the first time. She felt slightly less offended now. Yuzu pulled in a fortifying breath. Direct. Confident.

"I think I can help you. With the…" she gestured to her head. "Crawling around."

His eyes narrowed precipitously. This close, she couldn't _not_ be aware of the fact that he loomed. Her thoughts flashed back to Nnoitra, but she pushed them away. This was not the same as that. It was still dangerous, but it was different. This was a kind of danger she was used to. This was 'Eleventh Division officer doesn't want medical treatment' danger.

"The fuck are you talkin' about, woman?"

Yuzu pressed her lips together, then spoke. "I think that if you do _Jinzen_ , you'll be able to settle your thoughts. It'll be quieter—less crawling. I can teach you how."

She watched him war with himself over that. He didn't want to accept help. He was too proud for it. But at the same time, he wanted the result to occur. After giving him a few moments to work it out, Yuzu threw in what she _hoped_ would be the clincher.

"It'll make you stronger in a fight, too."

Admittedly, she was kind of hoping it wouldn't—she was well-aware that Grimmjow was an Espada, and likely to eventually face down officers of the Gotei 13 in battle. But it would also take a lot of work for _Jinzen_ to make a perceptible difference at that level, and she was guessing full-on war would be upon them in less time than it would take. But it _was_ just a guess.

It only took him a few more seconds to throw the door the rest of the way open and stalk back into the room. He slept on a pile of blankets and pillows on the floor, she noted—not a futon or bed as such. The whole room was much too big and sparse to really be _messy_ , but it had a distinct sense of being lived-in that most of them didn't manage. It also smelled faintly like someone needed to clean it. Not overpowering or anything, but—

Yuzu quashed her natural inclinations to tidy things and shook herself back into the present. Picking a spot on the rug, she sat down; with a gesture, she indicated that he should do the same.

"Do you ever have dreams where the spirit of your sword talks to you?"

"Talking ain't what happens."

"Um." She wasn't quite sure what to do with that. Still, they were in contact, at least. "Well, whatever happens, _Jinzen_ is a method of making it happen yourself. It also doubles as meditation though, and helps us get our thoughts under control. Usually I find that when I enter my inner world voluntarily, I have more control over what happens in it; if Hasuhime pulls me in, basically everything happens on her terms."

Basically everything did _anyway_ , but there was a perceptible difference, at least.

"Anyway, the one thing to be careful of is that, when you're in Jinzen, it's easy to lose track of what's happening in the outside world. So… maybe don't do it around certain people. You can come out of it whenever you want to, though."

"Yeah, all right. Whatever. How do you do it?"

She smiled mildly, unperturbed by his impatience. "Well, I can't give you a full demonstration, since you have to draw your zanpakutō, but you should lay it over your knees and hold it there. And then… try to clear your mind—of everything, not just the noise. If you can't do that, just focus on one thing." She paused to wait for the draw; Yuzu held herself stock-still when his sword rasped free of the sheath.

But he only laid it over his knees, like she'd said.

"If you find it's too difficult to clear your mind completely, then you can just focus on one particular thing—one that isn't in your head. So… if you wanted to stare at a blank wall, or light a candle, or just… focus on the sound of my voice, even. Whatever you pick, make sure it's steady, and doesn't make you feel angry or anything like that."

She fell silent, watching him close his eyes and try to go still. After no more than a few seconds, he scowled and cracked an eye open.

"What the fuck? Don't tell me to focus on your voice and then quit talking!"

Yuzu blinked. "Oh. Um. That was just an example."

"So? Keep goin'."

"About what?" Admittedly, she hadn't quite been expecting this.

"Like I care. Just pick something."

Yuzu bit her lip; figuring the talking was more important than what she was talking about, she started to tell him about her academy days; when she first learned _Jinzen_ and met her spirit. How she had a sister named Karin and a best friend named Uryū, how she loved kidō class but really struggled with zanjutsu.

By the time she was to her third month in, she was struggling not to cry. Remembering such a high point in her life—out loud, to someone who was technically her captor—was maybe not the smartest thing she'd ever decided to do. But Grimmjow didn't react, and she could tell from how _still_ he was that he was actually in the _Jinzen_ state by that point.

He probably wouldn't mind if she let a few of the tears in her eyes fall, then.

* * *

Rukia couldn't help the small sigh that escaped her when she lowered herself into her seat.

Across from her, Byakuya fixed her with a look. "Is something the matter?"

She shook her head, leaning forward to pick up the teapot and pour for them both. It was warm in her hands, but the thick ceramic meant she wasn't in danger of burns or anything. It wasn't until she sat back again, teacup resting atop one palm and wrapped with the other, that she answered.

"Not really. I mean, it's just that so many of my friends are in the living world right now; not knowing what's happening over there is a little…"

She took a sip of the fragrant tea. She'd advised Ishida to contact Yoruichi when he had the same problem, but she didn't exactly have a means to take her own advice. Ukitake-taichō did, but she didn't feel right asking him to borrow his communication device. It felt like overstepping something. Rukia knew she should trust her friends to be fine; after what Ishida had told her just before he left, though… she thought maybe being worried about them was justified.

"I cannot share the specifics of the reports given to the captains," Byakuya said, meeting her eyes across the table. "They are not particularly detailed in any case. But… I think at the moment there is no additional cause for your concern."

Rukia dipped her chin. "How are things at the Sixth?" They'd taken more of a hit than most divisions in terms of personnel; Renji and Karin both actually did a lot to help run the place. She figured that most of the work they left behind fell to her brother now—at least what he couldn't divide up among the other seated officers.

"Busy," he confirmed. "The Sōtaichō has placed ourselves and the Eleventh on active standby."

That was news to Rukia. "You think you might be deployed to the living world soon?"

A fractional motion of his head indicated Byakuya's disagreement. "It is unlikely. I believe he anticipates an attack on Soul Society itself. Given that our divisions are oriented towards frontline command and melee engagement respectively, it is not surprising that he wishes us to be alert. The Second has also been given orders to increase patrol volume around the Seireitei walls."

She frowned, leaning forward slightly. "But aren't both of those divisions currently without one or both officers? Why not put someone else on alert?"

"Such as?"

The mild tone of the question gave Rukia pause. She considered it. The First wasn't really a choice, since the Sōtaichō needed his division to help him run operations for the whole Gotei 13. The Second wasn't an open-field combat division unless it was absolutely necessary, plus they were already increasing patrols. Counting out the divisions with no captain, she was left with only a few: the Fourth, who obviously weren't front-line fighters, the Seventh, who had just lost their fukutaichō in battle, the Eighth, the Tenth, who currently had both an absent captain and vice-captain, and the Thirteenth.

"The Eighth and the Thirteenth," she replied. They were the only divisions not missing officers who didn't have a non-combat specialization.

Byakuya inclined his head. "Viable options," he agreed. "Too viable, in fact."

"What do you mean?"

Taking a long sip, he set his teacup down on the table. "Captains do not, as a rule, spend much time thinking about who among themselves are the strongest. It does little good even as an exercise, since the winner of a battle is determined by strategy and tactics more than outright strength—particularly at that level." He paused, mouth downturning slightly at the corners. "In addition, many of us are secretive about training and breakthroughs, so it would be difficult to ascertain even if there was any point in doing so."

Rukia was sensing a 'but' here. When it wasn't forthcoming, she prompted for it. "But…?"

"But despite all of this, I think it both distinct and obvious that—outside of the Sōtaichō himself—the strongest captains in the Gotei 13 are those of the Eighth, Thirteenth, and Fourth."

She suspected this was not an admission her brother would make publicly. But it was an interesting observation. Rukia hadn't spent a lot of time thinking about it, either, but she'd always sort of assumed Zaraki was the strongest captain, aside from Yamamoto. He did have the name _Kenpachi_ , after all. But if that wasn't so, then…

"You think the Sōtaichō is deliberately keeping those divisions in reserve," she said.

He nodded. "Yes. It is possible that the war will happen in the living world. It is likewise possible that it will happen in the Soul Society. The Sōtaichō is preparing for both possibilities—but he is making sure that those captains in particular are readily available to go wherever he needs to send them."

Rukia pursed her lips. The insight was helpful, but it did nothing to quell her apprehension. Not for her friends, and not in general.

"We… we really aren't sure what's going to happen, are we?" It had always felt like the _officers_ , at least, had a handle on events. Now that she _was_ an officer, it seemed like no one really did—that they were just projecting confidence to the rank-and-file. Her toes curled against her sandals.

"No," Byakuya replied softly. "We are not."

* * *

 _Term Dictionary_ :

 _La Loba_ – 狼后 – Kanji for "Wolf Queen;" the Spanish is roughly "she-wolf." AU!Starrk's zanpakutō. Since consistent worldbuilding means Lilynette as in canon can't exist, she's now the spirit in the sword. The release command is em _kechirase/em_ (蹴散らせ), "kick about."

 _Kagegaitō_ (影外套) – "Shadow Cloak." One of Yorugen's shikai abilities. By splitting his shadow into two and shrouding himself in one of them, Uryū is able to completely conceal his own reiatsu, as well as distort things around him. It creates a blur or displacement effect that makes it harder to judge his exact position, thereby making him harder to hit.

* * *

All right, so… Karin's having some problems with bankai, Uryū and his dad have some serious issues to work through even outside their training, and Yuzu is worming her way ever closer to some of the more hospitable Espada. (And some of the less hospitable ones who still aren't complete jerks to her).

By my current best estimate, the next chapter will cover the next day or so in some detail, then a month or two in less detail, and then we'll finally be ready for the next phase of the story with a major plot event that almost everyone in-story has been waiting for.

Hope you're ready for this ride to get the go-faster stripes. :)


	10. Chapter Ten: Quite Prepared to Die

.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Ten: Quite Prepared to Die

* * *

Karin had aches on top of her aches. Every muscle and tendon she could feel screamed at her to slow down, to stop, to give up and rest. Some of them, she _couldn't_ feel anymore. She held onto her sword's grip only barely in shaking fingers, slick with sweat and blood. The ring had only gotten hotter and hotter as time wore on and Hisaku exerted more of her power. The spirit had sliced the tie out of Karin's hair a long time ago—the whole mass of it was plastered to her neck, shoulders, and face.

Half the upper part of her shihakushō was gone; she'd cut it off as soon as it had caught fire, hoping to avoid the burns. She had one half of it and her sarashi bandages left. Actually…

Karin shrugged out of what was left; the air on her skin was only barely any relief, but it was a little better than sweating right through the fabric. Nicking the sleeve with her blade, she tore a strip off with her teeth and used it to rebind her hair. The burn marks from the injuries she'd cauterized pulled—uncomfortable reminders of the price she'd already paid to still be standing. If she'd let them all bleed, she'd have passed out by now, but burning them shut wasn't painless either.

Hisaku wasn't perfectly put-together, either. Karin had to work to make her fire hot enough to do anything to the spirit, but it _was_ possible. She'd discovered that a little over halfway into the second day. Now, near the end of the third, Hisaku sported several shallow cuts and three patches of scorched plumage, but only that.

"Give up, Karin." Hisaku leveled her sword outwards. "It is not time for this yet. You don't have the strength to handle my power."

Karin's jaw clenched; it was impossible to hold her sword in the right position with only one hand now. She needed both to lift it. Even then, the tip of the blade trembled. "Stop telling me to do that. I'm not gonna, so you might as well save your breath."

She kicked off the ground, throwing herself forward into the next pass. Karin aimed for Hisaku's left shoulder; the spirit raised her katana to block. The hit ricocheted all the way up Karin's arms, jarring the exhausted muscles painfully. Hisaku disengaged quickly and scored a slice across her collar; Karin leaned away, just barely preventing it from scraping bone.

They jumped away from each other, resetting their positions. Blood dripped onto Karin's bandages, staining their upper edge red. She pulled in a deep breath—too deep, from the stabbing pain of the stitch in her side. Grunting, she scrunched her face and went into stance again.

"There is no point to this. People stronger than you will be able to rescue your sister, if she can be rescued at all. You do not have to do it yourself—"

"Of course I do!" Karin snarled. "You don't leave your family for other people to take care of. You protect them yourself, with your own hands. That's what family is!"

Not everything it was. But definitely one of the most important parts.

Another pass, another new injury.

"Who cares, as long as it's done?" Hisaku pressed. "Wouldn't you rather someone else saved her if the alternative was that she was never saved at all? Don't you trust anyone else to succeed? Don't you trust _her_ to save herself?" Bright gold eyes looked down Hisaku's painted nose at her.

Karin shook her head. "You don't get it! Of course I want her to be safe. Of course I trust her. This isn't that, it's—"

"Another obstacle you have built up in front of yourself. After all this time, you still only know one way to solve a problem."

"Some problems don't _have_ other solutions!" Karin's hands tightened until it hurt. "Sometimes you have to fight for things and there's no way around it! You think I want this? You think I _want_ Yuzu to be over there with those assholes, in danger? You think I want to have to… to kill people to get her back?"

She didn't want it. She didn't want this. Not any of it. But it was the hand she'd been dealt, and she had to find a way to make the most of it. To fix things.

"Yes," Hisaku replied, blinking slowly. "I think you do."

"Fuck you!" Karin dumped as much reiatsu as she could stand into her blade, increasing the flames on it to a bonfire. They licked at her hands and face, but her own fire at least had never burned her, and it didn't start now.

Throwing her body into a spin, she increased her speed until she couldn't go any faster, timing the _Habatake_ so that the fire left the blade right at the height of her motion, surging forward for where Hisaku stood. Halting herself by planting one of her feet and dragging it along the ground, Karin willed the flames to split and attack from different sides.

But Hisaku was incredibly fast, and by the time the fire came back together, she was gone. Karin _just_ ducked the counter—Hisaku's fire had threads of white in it, added to the orange and red. The spirt followed up, unrelenting; Karin was driven back against one of the few intact rock formations left in the basement. Hisaku stabbed her blade into it, centimeters from Karin's head, leaning down until they were nearly nose-to-nose.

"You do," she said. "You want it to be this way because you know that war is when heroes are made. And those heroes look like you." Hisaku curled her lips, baring several of her teeth in a smile with no joy in it. "You've already killed once. You know you have what it takes to do it again. And you want, so _badly_ , to succeed at something. To stand out. To be so good you cannot be touched. Peace will never give you that opportunity."

Karin struggled, but Hisaku effortlessly pinned her wrists to the stone with her free hand, talons digging into her skin. "You're not a diplomat. You're a warrior. And this is where you belong."

Unable to move, feeling her resolve weaken, Karin panicked. "Shut _up_!" She lashed out with a burst of raw reiatsu. It combusted in the air, causing an explosion in the space between her and Hisaku.

The spirit reeled back; Karin half-stepped, half-fell forwards. It was almost by accident that her sword found Hisaku's guts, but it did; the momentum of her bodyweight pushed it out the other side. She was too weak to move; even like this, Hisaku was the one propping her up, not the other way around.

"I don't want… to kill anyone," she breathed, struggling to manage even that much volume. "If I have to… then I will. But I _don't_ want to." Her throat felt like sandpaper; she couldn't even put up a fight when Hisaku raised a hand and took hold of the sword in her stomach.

"I do want… I do want to be strong. I want to prove it to everyone, and… maybe… maybe you're right that I will, because of this."

She swallowed; it felt raw all the way down. "But you're wrong about why. If I… if I'm strong enough, then… then people will have to listen when I talk. And even if I'm not… a diplomat… I can still… protect them. War or no war."

Hisaku stepped off the sword; when she let go, Karin slumped forward. There was nothing to hold her upright anymore. The spirit caught her, though—the feathers on the headdress filled her blurry vision.

"You still have far to go," Hisaku said. "But for now… I will lend you my strength."

Karin blacked out.

* * *

"I don't mind it if I can see you, you know." Yuzu looked directly at the kitchen door. Her shadow usually stayed fairly far away; for some reason whenever she was in here, though, he stood closer, usually just on the other side of the doorway, against the near wall.

She didn't expect much of a response, but he did actually come in—he still kept his distance, however, taking up a spot on the further side of the room. She went back to tending the miso in a pot on the stove. Normally, she was a little more ambitious with her cooking when she was only going to eat it herself—but it had been nothing but comfort food in the last week. She accepted her need for it, and tried to keep from thinking too much about why. It was enough that danger lurked nearby at every moment; if she dwelled on it too much, she'd drive herself mad, no matter what Starrk said about her sanity.

"How are you today, Ulquiorra?" She was aware of the irony of asking after the feelings of someone who displayed such skepticism about their existence; that was one of the reasons she did it.

Yuzu's only coherent plan at this point was making herself harder for them to kill. Maybe, if she stayed alive long enough, she could gather the resources for an actual escape plan. Anything to that end now, though, would be far too premature. So she focused on smaller things instead. Trying to get Ulquiorra to accept the validity of emotions wasn't exactly a _small_ task, but it wasn't at the level of somehow outsmarting _Aizen_.

"The same as I was when you asked yesterday," he replied flatly.

She figured that since her back was to him, he couldn't see her little smile. "And the day before that?"

"…yes."

She shook her head slightly. Though sometimes the inclination to tease him a bit was there, she knew he wouldn't quite understand. Besides… Yuzu couldn't be so sure it wouldn't fall completely flat. Moments of levity were few and far between, here—and she knew they could be dangerous. Could give away too much. They were, after all, a sure sign that she'd let her guard down.

She'd have to, if she was actually going to succeed in making any friends here. But Yuzu knew she also had to be very, very careful about it—if she could.

"I suppose it can't make for much variety, following me around. I don't really do anything very interesting, these days."

Ulquiorra offered no comment on that, and she didn't demand one.

At length, though, he broke the not-quite-comfortable silence. "I thought about what you said."

"Can you be more specific? I talk a lot, compared to you." Yuzu moved to the cutting board, slicing tofu into small cubes.

"You said that feelings are caused by something called the heart. I believe you were mistaken in asserting this. Feelings are illusory."

Yuzu carefully transferred the tofu into the miso pot, scraping off the cubes that stuck with the flat of the knife. "Illusory? Doesn't that seem even more implausible to you than what I said?"

She heard the soft rustle of fabric behind her—probably he'd just slid his hands into his pockets.

"No. What is most implausible is that there is something that exists and yet cannot be apprehended by any of my senses. My pesquisa has no blind spots, and yet I have never seen a heart."

Yuzu resisted the urge to sigh, stirring the soup gently. "Have you ever seen gravity?" She turned to look at him over her shoulder.

He was silent.

"It still exists, surely."

"Gravity has observable manifestations, for which the existence of gravity itself is the best explanation."

Well, he was in quite the philosophical mood today, wasn't he? Yuzu was suddenly glad she did so much _reading_ , or she might be at quite a loss for what to say. "So you'll accept that something exists if it's the best explanation for something else?"

"Yes. Provided that it, as well, can be reasonably explained."

She really did sigh that time. The soup was coming to a boil—the familiar, homey smell permeated the kitchen. "Well, all right then. The existence of emotions, of a heart, as you say… is the best explanation for the fact that I love my sister." That was a fairly straightforward example.

From the corner of her eye, she saw him shake his head.

"Humans, and by extension shinigami, evolved to survive. To avoid pain. That is simply instinct. Forming what you call bonds with others is one way to increase one's own chances of survival. You feel something that you believe is love because it is beneficial to you."

"Of course it's beneficial to me," Yuzu replied easily. "I have a much better life because of Karin. And she has a better life because of me. Even if those things only came about because at some point our species needed them to survive, it doesn't follow that they aren't _real_. Doesn't their necessity just make them a better explanation?"

Ulquiorra paused for a moment. "Then where is it? This heart? Where do I find it? If I dug into your chest, would it be there? How about if I split open your skull?"

Yuzu swallowed. She'd almost forgotten, for a moment, where she was and just whom she was dealing with. "The metaphor is named for the thing in the chest," she said carefully. "People used to think it really was there. The chemistry part happens mostly in the brain, so I suppose in some _literal_ sense… it would be there. But, if what you wanted was to really _see_ it…"

She ladled some miso soup into a bowl, setting it down on the counter and offering a tentative smile. "I suppose you might want to start there."

"That does not make sense."

"If you want to see a heart, the best you can do is seeing what it causes. Just like the only way to really _observe_ gravity is to watch things fall. It's there, in what you could see all along."

Ulquiorra still only stared at her. Yuzu pursed her lips.

"My mother," she said softly, "wasn't actually a very good cook. But she was a bit better than my father, and she made very good miso soup. I don't remember much about her, anymore, but I remember that." She ladled a second bowl for herself and sat down at the table in the kitchen, setting his untouched serving down diagonally to herself.

"I don't even like the flavor that much, to be honest. But whenever it's cold or I feel like I… need to be reminded of her, I make it. And I share it with other people, because I want them to feel the same way I did, when she made it for me." She stirred around the tofu in her bowl with her spoon.

"No matter where I am, or what I'm doing… I feel better. And that's illogical and strange and doesn't make any sense, I know. But that doesn't make it any less real." She took a sip, feeling the warmth seep all the way down to her stomach.

Tilting her head to the side, Yuzu met Ulquiorra's eyes. "But if for you it's only lunch, that's fine. I promise it tastes good—and I made too much, so it'll go to waste if you don't eat any." She knew the Arrancar ate—since everything here was made of reishi, it was logical that they would. Apparently, food like the kind from the Soul Society would do well enough; maybe because they were sort-of shinigami now.

Wordlessly, he sat. His first taste was tentative, but it didn't seem to offend his sensibilities, at least. She made no further comment on the subject. He could consider her words or not—she couldn't force him to do anything he didn't want to. Nor would she desire to, when it came right down to it.

But maybe the fact that he'd thought about their last conversation at all was a good sign.

* * *

How long had it been? Five days? A week?

Uryū had lost count after four; he no longer had any idea how much time had passed. Ryūken was apparently fading, but not nearly as fast as Uryū was. Constant _shunpō_ and kidō and keeping Yorugen in shikai had finally drained him of reiryoku; he was now down to his last resorts: the gintō.

He wasn't without damage, either; his left sleeve and the right half of his uniform were completely shredded. Too many near misses. Of course, they'd likely have been hits if he hadn't kept _Kagegaitō_ active; as soon as he'd been forced to drop it, Ryūken's accuracy had spiked, and a few of the arrows fired since had struck true. Uryū bled from two punctures in his left shoulder, another in his right calf, and one near his right hip—he'd had to twist hard enough to pull something to prevent that one from hitting a vital organ.

Ryūken's only injury was a jagged cut on his right arm—Uryū had attempted to incapacitate him with the last of his reiryoku. The slice was too shallow to actually sever the muscles, however, and accomplished little beyond bloodying the white sleeve of Ryūken's shirt.

He wasn't taunting him anymore, though; they'd both mostly stopped talking a couple of days in. Without _shunpō_ , Uryū was leagues slower than his opponent; he had to read the trajectories of the arrows as they left Ryūken's bow to have a hope of getting away from them.

Even that wasn't going to last.

With a crash, the platform Uryū stood on lurched underneath him. Drawing to a sudden stop, he pitched forward when the ground crumbled beneath his right foot; he flipped open one of the gintō on his way down. " _Wolke._ "

Light blue reiatsu hissed out of the tube, enveloping him in a thick cloud of pressure that slowed his fall. Uryū landed easily on his feet, in just enough time to roll out of the way of the next three arrows. With no reiryoku left, he was stuck on the lowest level of the training room—his movement confined to corridors and blind turns. No doubt for Ryūken it would be like shooting a fish in a barrel.

Which meant he had to do something decisive _now_ , or he'd never have a chance.

His fingers tightened over his one remaining gintō. Ryūken tended to pause between each volley of shots and wait for the smoke to clear before he fired again. He also didn't move unless he found it necessary—meaning that if it didn't seem likely that Uryū would attack, he'd remain where he was. Grimacing, Uryū darted to the right; as expected, more arrows followed. He ducked around a corner and immediately jumped, boosting himself with the tiny trickle of reiryoku that he had left.

Catching hold of one of the edges of a raised platform, Uryū hauled himself up. As soon as he had a visual on Ryūken, he threw the last gintō. A thin ribbon of liquid spirit energy trailed from the tube, and Uryū focused on it.

" _Gritz_."

The liquid split almost into a net shape, closing over Ryūken from the side. Uryū just glimpsed Ryūken's eyes widening before the spell took full effect, solidifying into a person-sized enclosure and melding into the ground.

He pulled himself up the rest of the way into the platform, panting for breath. Bracing his hands on his knees, he managed to straighten into a stand—

Only to feel the sudden pain of an arrow right in his chest. Uryū choked on his gasp; his vision whited out. He only barely registered the smoking hole in the _gritz_ and the figure walking towards him before his thoughts halted completely.

* * *

When Karin came to, she was alone in the room she shared with Yoruichi, Rangiku, and Yachiru.

Her pain had been reduced to a dull ache; when she flexed her hands, her fingers scraped over bandages. Tilting her head, she saw that someone had put her in a clean robe, but she felt plenty more gauze and wrapping underneath it. Still… she obviously wasn't doing as badly as she had been when she passed out.

A new knowledge sat at the back of her mind, too. Turning her head, she found Hisaku with her eyes. "Thanks," she muttered.

 _Do not forget what I said_.

Karin was tempted to ask which part, but she knew. She had a long way to go. Fair enough. As long as she got far enough to help Yuzu, she could work the rest of it out later.

Clenching her jaw, Karin half-rolled to the side, planting both hands on the floor and pushing herself up into a sitting position. It took less effort than she'd thought it would—maybe Tessai and Iemura had had a couple days to work on her? Standing was a bit more of a trick, but she managed it. She had to—she felt a gnawing pit where her stomach should be. If she didn't eat something soon, she'd probably just pass out again.

She didn't so much walk as lurch to the door, but it got the job done. Fumbling with the latch, she swung it open, heading for the kitchen with singleminded intent.

That was probably why she managed to miss the fact that Hitsugaya was just leaving the other room across the hall until she'd already clipped his shoulder with hers. Unfortunately, with the state she was in, the impact jarred her a lot more than him, and she was halfway to the ground by the time she caught herself on the wall. It was that and the fact that he'd gripped her by the forearm that stopped her from falling.

"Dammit." At least she hadn't landed on her ass, she supposed.

"Are you sure you should be walking around?" he asked, letting go as soon as she was balanced again.

Karin frowned at him. "I'm hungry, so I'm going to eat."

Inevitably, he frowned right back. Karin would never admit it, but it was possible that he made an even better scowler than she did. But he didn't argue any further, and she continued until she reached the stairs. Those were a bit trickier to navigate; she had to take them annoyingly slowly, placing each foot down and testing to make sure it would take her weight.

Hitsugaya followed her down, offering no commentary on the pace of their descent. It kind of annoyed her that he was there at all, but at least he wasn't being an ass about it.

"Where is everyone else?" she asked, because the silence was awkward and left nothing to focus on but how hard she had to try to walk down the stairs.

He took another step downwards when she'd cleared her own. "A few Hollows appeared in town about fifteen minutes ago. They've gone to deal with it."

"Arrancar?"

He shook his head. "Unlikely."

"Then why did they _all_ go?"

He rolled his eyes. "I only sent Matsumoto and Abarai. But Zaraki wanted to go, and where he goes, Kusajishi follows. I asked Iemura to make sure they don't kill themselves. The others are just out getting supplies."

Another step; Karin leaned heavily against the rail. "Any leftovers in the fridge?"

Hitsugaya shrugged. "Maybe."

That wasn't exactly a great answer, but whatever. She'd have to get down the stairs eventually anyway—whether that was to eat now or tear into something when the others came back with groceries really didn't matter in the long run.

Finally, she reached the landing. After that, getting to the kitchen was pretty easy. She opened the fridge door with a grunt and bent over to stick her head in. The shelves were pretty bare, but she spotted what looked like some of Tessai's curry near the back and pulled it out.

Not even bothering with reheating, Karin tossed the tupperware onto the counter and grabbed herself a spoon—chopsticks would be way too slow. Hopping up onto the stool, she pulled the lid off the container with the slight crinkle of plastic and dug in without ceremony. The rice was hard and nearly flavorless because of the cold, and the spice barely registered on her tongue, but it was edible and she was starving, so it was just about the best damn thing she'd ever tasted.

Hitsugaya took a seat on the other side of the island. It was probably rude to just scarf her food in front of a captain or whatever, but Karin had no fucks left to give right now.

"'ow lon' was ah out?" she asked around a mouthful.

He crossed his arms; a line appeared between his eyebrows. "Two days."

Well, that explained the hunger, at least. Karin nodded, shoving another spoonful in her mouth and trying not to chew too fast.

"You have bankai now," he said; she thought she sensed a question in there somewhere.

Karin felt a little swell of pride at the reminder. Yeah, it hadn't been easy, and she'd done it for more important reasons than her own satisfaction. But that didn't change the fact that it felt _damn_ good. Bankai was something that most shinigami only ever dreamed of. And she had one.

She swallowed, wincing when she realized she hadn't quite chewed enough. "Yeah," she replied. "I do."

Hitsugaya nodded. "You'll need to train it before it becomes very useful, though. The best way to do that is to use it against something of comparable power."

Karin had figured as much. Slowing down slightly on the food, she cocked an eyebrow at him. "You offering? Cause I'm pretty sure the last time I wanted to train with you, you said 'it would be a beating.'" She imitated his snobby tone, unconcerned that she was exaggerating it.

"I wasn't—" He cut himself off with a shake of the head. "It doesn't matter. I was actually thinking of Abarai when I suggested it."

She considered that. Renji did have bankai. He was also a good training buddy; she knew that from experience. But his bankai was melee-type. He'd be damn _fun_ to spar with, but by this point, the amount of advice he could give her was probably limited.

 _You still have far to go._

Karin pursed her lips. "My sword's an elemental kidō-type," she said, meeting his eyes. "Just like yours." Pulling in a big breath through her nose, she swallowed her pride. "I need to get as good as I can as fast as I can. To do that… I should train against the person who can teach me the most."

There was a beat of silence. Karin shifted uncomfortably in her seat. "Hitsugaya-taichō… would you please help me learn how to use my bankai?"

"Uh…" he looked like he had no idea how to respond to that.

She figured that was fair—it wasn't exactly like her to ask for something that way. But being awkwardly polite was a small price to pay if he agreed. She kept her eyes on him expectantly.

"Fine. But not until someone can fix the rest of those wounds and do a reiatsu restoration. It won't do any good otherwise."

* * *

Unsurprisingly, dinner with Ryūken was uncomfortable.

He'd awoken in a hospital room the day after his collapse, a new tattoo—or maybe a scar?—he didn't recognize right at the center of his chest and with complete certainty that, in his inner world, Lucia was awake.

Before he'd been able to properly investigate this development, Ryūken had entered. Apparently, the process he'd just been put through was an extremely rare Quincy technique for restoring lost power: by completely draining the intended recipient of all energy and firing a Heilig Pfiel nineteen millimeters to the right of the heart, someone could break the seal placed on that person's Quincy powers after _Letzt Stil_.

 _Why_ Ryūken had chosen to do this—as well as why _now_ , instead of in the two years after Uryū had lost his powers—was less clear. He hadn't volunteered the information, and Uryū hadn't asked. He'd considered just leaving after he'd been discharged from the hospital, but Ryūken had more-or-less told him that there was more to be said. Despite his own misgivings, Uryū acknowledged that Ryūken clearly knew more than he'd previously demonstrated.

Without anyone else to teach him those things, he was stuck here until he learned them.

The house was just about as clean as the hospital—and just about as impersonal. The sparse visible belongings were all functional; what wasn't white was grey or black or dark blue. Everything was at home on a shelf or in a drawer; no dust lingered even in the far corners. He wondered if Ryūken still had the cleaning service take care of it. Likely, considering the hours he worked at the hospital. If he hadn't bothered to come home until late at night when he actually had a family, Uryū couldn't imagine him doing so _now_.

The kitchen was glass and chrome and marble; he couldn't help but compare it to the slightly-cluttered one in the shop or the warm, soft colors and mellow wood of the Kurosaki house.

They ate in silence; Uryū had cooked, but then he'd been doing that most of his life. He kept his eyes resolutely fixed on the food in front of him, doing his best to forget another person was in the room at all. It wasn't easy—he failed all together when Ryūken suddenly spoke.

"How much time do you plan to spend in the living world?"

Reluctantly, Uryū lifted his eyes, meeting Ryūken's. When he was a child, he'd been happy whenever someone mentioned how much he resembled his father. Now he couldn't stand it.

"I don't know. It depends on how soon they can find a way into Hueco Mundo."

Ryūken's eyes narrowed. "Then you're going to have to learn quickly."

"Why are you doing this?" Uryū hardly wanted to push his luck, but the question was burning a hole in his stomach. If he didn't ask it, it might wear all the way through to the rest of him. "Restoring my powers, teaching me… whatever you're going to? Why bother, when you've given up being a Quincy?"

"Just because I see no point in it doesn't mean I'm willing to allow a talentless child like you to wander around calling yourself the Last Quincy. Much as I might dislike it, that title belongs to me. It therefore falls to me to make sure no one who calls themselves such a thing is an incompetent fool."

Uryū gritted his teeth, tightening his grip on his utensils until his knuckles were white. Ryūken was baiting him; he knew that. Five years ago, he would have bitten anyway. A muscle in his jaw jumped. He forced his breath out slowly.

"We'll see who's incompetent," he replied quietly.

* * *

She was watching them train when it happened.

A month wasn't nearly long enough to master a brand-new bankai, and Karin's seemed especially difficult to control. But at least she mostly had a handle on the release now. Things got a little dicey after that, but Tōshirō's ice was actually pretty helpful in keeping it contained. Yoruichi was pretty sure the training was useful for him, as well.

She was thinking of suggesting they move things to the air, since both of them had flight capability. But before she could call down to them, she felt a shift in the reiatsu of the area. On her feet instantaneously, Yoruichi jumped down all the stairs at once and landed on the ground.

"Stop, you two!"

They pulled up mid-motion, turning to her with comically-identical frowns. She would have laughed if it were any other situation.

With a shudder and a crack, space momentarily tore open in the center of the training area, and a familiar pair of gates rose out of the ground. The looming skeleton torsos on either door were impossible to mistake.

For a moment, Yoruichi felt a sudden rush of hope, the first in too long. Could it be? But her practicality demanded she consider all possibilities, and almost nothing that could come out of gates like those was good.

"Shit." Obviously, Karin felt the same way.

Yoruichi approached the gate with caution; electricity crackled just under her skin. If she needed it, she'd be able to enter _shunkō_ in half a second. With a slow, grating creak, the doors swung inwards, and through them stepped—

"Kisuke!"

His face was unusually gaunt, and he looked like he hadn't bothered to shave in several days—his stubble was halfway to an actual beard. She could see dirt under his fingernails and his hat had a chunk suspiciously missing from the brim. But it was obviously him all the same.

At the sound of her voice, he turned to peer at her. His stupid asinine grin stretched over his face like it was completely appropriate to the situation.

"Hey there, Yoruichi. Miss me?"

* * *

 _Term Dictionary_ :

 _Sarashi_ – 晒 – "Bleached Cotton." A long strip of cloth, generally worn by men from the midriff up to the chest, and by women from just beneath the armpits to the navel. Traditionally worn to help resist injury (by warrior types), or as a form of breast-binding. Karin's pulls double-duty.

 _Wolke_ – 緑杯 – The kanji mean "Green Cup" for some reason. The German is "Cloud." A Quincy spell that uses the energy collected in a gintō to cushion a fall. For reference, these are the same gintō from like… chapter one of TTBP. Uryū has been carrying them around for _that_ long.

 _Gritz_ – 五架縛 – Kanji are "five rack ties." It doesn't mean anything in German, as far as I can tell. It's a Quincy spell that forms a sort of coffin-like enclosure over the target. Kind of like a bakudō of sorts.

 _Heilig Pfiel_ – 神聖滅矢 – The kanji mean "Sacred Destruction Arrow;" the German comes out to "Holy Arrow." The proper Quincy name for the arrows they fire. Ryūken's are white; Uryū's are light blue.

* * *

Aaaaand that's when she punched him. Not really, but it was extremely tempting, I'm sure. Anyway, Urahara's back, and we all know what that means. :)


	11. Chapter Eleven: In for Nasty Weather

.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Eleven: In for Nasty Weather

* * *

"That will be sufficient for now. Thank you, Yuzu."

He could see the rapid calculation behind her eyes. She was wondering how much more it would take before the object cradled in her hands was repaired completely, and she was no longer necessary.

She counted the days to her death.

Of course, it was by design impossible to accurately estimate. He called her here at random intervals—sometimes two days in a row, sometimes with a week between summonses. It kept her consistently on edge, and Sōsuke could see all the ways it was beginning to wear. She still held herself well, but the fatigue was easy to read in the dark circles under her eyes. She slept poorly, he knew. What was more, he knew she did so only when she could feel the reiatsu of one of her "friends."

So she thought of them, he expected.

"You are dismissed," he said.

She nodded—she never bowed—and took her leave, glancing expectantly at Ulquiorra.

What Yuzu failed to understand was that an Arrancar was still fundamentally a Hollow, and a Hollow was a thing without such sentiments. Their surface behavior could change as necessary—some of them understood to a certain degree things like obligations, debts, and mutual benefit. But they were not creatures of sentiment. She could reach out all she wanted—in the end, she would grasp only empty air.

And yet…

"Not you, Ulquiorra. Please remain a moment."

The Arrancar, who had started to turn to leave after Yuzu, halted immediately. Sōsuke's eyes narrowed slightly as both of them paused, just for half a second. There was clear communication in their expressions—even Ulquiorra's lack of one. It was gone in a mere moment. Nevertheless, it was only then that she left and the Cuarta turned to face him.

Between two humans or shinigami, it would have been nothing. A simple acknowledgement. But one of them was neither; he shouldn't have been able to pick up on such a subtle thing, let alone react to it in kind. The meaning of the exchange was obvious when Yuzu's reiatsu stopped moving away as soon as she was a polite distance from the chamber.

 _Wait_ , it had meant.

Well, well.

Ulquiorra's expression was as flat as ever now, of course. Sōsuke turned the Hōgyoku over and over in his fingers. One more restoration, and it should be back to its perfect state, ready to present to the other. Yuzu's life lasted as long as he wanted it to, now.

"How is our guest coping?" He asked, taking his chair with graceful ease. "She has been with us for… nearly forty days now, hasn't she?"

It was thirty-nine exactly.

Ulquiorra blinked impassively. "She is as she appears," he said.

Sōsuke crossed one leg over the other, leaning his jaw into his free hand and studying the Hōgyoku's surface. "And her interactions with the Espada?"

"Are limited. Starrk hovers. Grimmjow sniffs around occasionally. Nnoitra frequently expresses his displeasure at her continued breathing. He has not approached her since the first time, however."

"Ah, yes. That would be your doing, would it not?" Sōsuke glanced up from the orb's dark purple surface and locked eyes with Ulquiorra.

The Arrancar's expression did not change. "She has been compliant. Physical harm was unnecessary. And since Nnoitra is not known for his restraint, there was a chance he would have defied your orders. I preempted the situation."

"That is all?" Sōsuke lifted an eyebrow.

"That is all."

He felt one corner of his mouth lift. "And I suppose the food is merely food?"

There was a slight pause; long enough to be noticeable. "Even I must eat. The food is convenient, as my duties place me in her proximity in any case. Logically, completing two necessary tasks at once is preferable to completing them in sequence, all else being equal."

"And what is your opinion of her mental state?"

Another pause. "She has fortitude. How much longer it will last her, I cannot say. I suspect that what she calls 'hope' is beginning to thin. How much longer do you intend to keep her alive?"

"A question?" And not a strictly necessary one. Sōsuke's eyes narrowed.

"I inquire only to know when I resume my former duties."

"I have not yet decided," Sōsuke lied easily, closing his fingers over the Hōgyoku. "You are dismissed."

Ulquiorra bowed and left. Sure enough, that was when Yuzu's reiatsu moved as well—both of them headed towards the kitchen.

He doubted very much that the Arrancar understood the significance of such little things. They were trifles, in any other situation—things another might not even have noticed. But Sōsuke noticed, and he understood that there were times when what was otherwise trivial counted for more than it seemed to.

He would call for her again tomorrow, and then she would die.

* * *

Tōshirō scowled, trailing frost behind him as he left Urahara's room and the screen that projected the Sōtaichō. After all of this… he couldn't believe it.

Well, no, that was false. He _could_ believe it. He just wished he didn't have to. Opening the door to the room most of the shinigami shared, he found that nearly everyone was in it. Only Abarai and Iemura were missing—patrol. They'd be back soon, anyway.

"So?" Kurosaki asked. "Have we got the permission or what?" It took her a second, but she seemed to register his expression; her face hardened by degrees. "You've gotta be kidding me. They don't want us to go?"

"It's worse than that," he replied. "The entire advance team is being called back to prepare for Aizen's next move. We must return to Soul Society immediately." Tōshirō reached into his pocket for his denreishinki. Abarai and Iemura needed to get back here as soon as possible. The Sōtaichō had made it clear that the orders were urgent. As though there was something back in Soul Society that they were necessary for.

He might not have been a captain for very long, but Tōshirō knew false implication when he heard it. Probably he just wanted them back so that he knew exactly where they were.

"That's fuckin' stupid," Zaraki said, scratching his jaw. His calluses rasped over leathery skin. "If Aizen wants a fight, we should be takin' it to him."

It wasn't the soundest tactical move, but it wasn't completely without merit. Especially in the crucial couple of days between when Urahara got back to the living world and Aizen _realized_ he had. It was the closest thing to an ambush opportunity they were ever going to get. They should be capitalizing on it, not withdrawing even tighter into a position they might not even need to defend. At _least_ they should be protecting the town their enemies were so interested in.

Sending the message, Tōshirō looked up. The moment his eyes landed on Kurosaki, he knew there was going to be a problem. Her face had no hostility, but he recognized the look in her eyes. It was the same one she wore when she was down but not out in a spar. Absolute, stubborn refusal to do what would be easiest.

"I'm not going."

He blinked at her. Suppressing the instinct to lecture or snap irritably, he reminded himself that she wasn't thoughtless about this. Tōshirō slid the denreishinki back into its spot between the layers of his uniform. "Disobeying the direct orders of the Sōtaichō is an act of treason, Kurosaki," he said quietly.

"You gonna arrest me, Hitsugaya?" She crossed her arms over her chest.

He looked away, focusing on a corner of the room. He _should_. But he knew he wasn't going to.

"…No," he said at last. "But you should get out of here for a while. I think the Sōtaichō might know we're not too happy about this and send someone to make sure we do what he says. You won't want to be here when that happens."

He glanced back. She looked surprised—but she quickly recovered, nodding. "I get why you guys have to go back," she said. "If it means anything, I'm not mad at any of you. But I can't just leave her there. Not when there might finally be a way to get her back."

Tōshirō nodded. "Good luck." There was no way she'd succeed by herself. Even if Ishida was taken into account… there were just too many Arrancar, and they were too powerful. But she knew that. She'd chosen it anyway.

He knew someone else like that.

Kurosaki pulled open the room's window. "Tell the monkey I'm sorry about this." Placing her foot up on the sill, Kurosaki jumped out—her reiatsu moved quickly after that, then disappeared. None of the others even attempted to stop her.

It was then that the Senkaimon opened, and two Kuchikis stepped out.

* * *

Karin couldn't sense Uryū's reiatsu; she figured he was probably in some training area that blocked it out, kind of like the one in Urahara's basement. But she knew where he'd be—he'd told her that his old man ran Karakura Hospital.

By the time _shunpō_ had taken her to the right city block, she could feel a small thread of his spirit energy; it was enough to help her figure out that he was underground. There were windows right at ground level around the back side of the hospital—but they had one-way glass from the inside out, meaning that she couldn't see what was going on inside.

Still, there was no mistaking that this was there the reiatsu was coming from. Karin knocked sharply on the window—it didn't seem to open from out here, but there was a chance it did from in there.

A few seconds later, there was a slight sucking sound as the glass panel popped free of its rubber seal, and Uryū poked his head out. His hair was messed up from moving around, and she could see tiny beads of sweat along his forehead and cheeks. His skin looked slightly… blue? Was he cold or something?

"Is it time?" he asked.

Karin swallowed. "Close, I think. But… the others have been called back to Soul Society. The Sõtaichō isn't going to let them go."

He pursed his lips, eyes narrowing. "And you?"

"I was supposed to go back too, but I'm not going to."

Uryū only nodded. He didn't try to talk her out of it, and she had no doubt he'd be coming with her. While Karin _would_ have gone alone if she'd had to… she couldn't deny that she was glad she'd be going with him.

"All right," he said. "Give me a few minutes, and I'll be out."

* * *

Uryū let go of the windowsill, landing lightly on one of the training room platforms. Ryūken—sans suit jacket and with sleeves rolled up—dismissed his bow with the flick of a wrist.

"I take it this means you're leaving." He sounded the same as ever—cold, nearly toneless. Really, the only variation was the occasional sliver of disapproval; oddly enough, Uryū didn't hear it just then.

He answered the question with a spare nod, then elaborated. "Most of the others have been called back to Soul Society. Karin and I have to go while we still might have the element of surprise."

"The Kurosaki girl."

"Yes." Uryū didn't know why he was bothering to explain—it wasn't like Ryūken gave a damn about shinigami. He barely gave a damn about anything to do with the _Quincy_ , for that matter.

And Uryū could scarcely comprehend the idea of _not_ standing for something. Go figure.

"Her sister has been abducted by Aizen and the Arrancar. Yuzu." The worry he'd been quashing as well as he could for the past month and some days flared again. It was a little contraction in his lungs, like someone had wrapped a hand around each and begun to squeeze.

He thought about mentioning that their mother was a Quincy. And with a Japanese name like that—surely Ryūken must have known her at some point. But from the way he'd brought it up, Ryūken had already realized the connection, whatever it might have been. If he wasn't going to share, then that was his problem. The important thing was getting Yuzu back.

"Follow me." Ryūken turned, hopping off one of the platforms and into the corridors that divided them into neat sections.

Furrowing his brows, Uryū pulled in a breath and went after. In the far southeastern corner of the room was a door he hadn't noticed before. Withdrawing a key from his pocket, Ryūken unlocked it, turning the handle and pushing it inwards.

Automatic lighting flickered on overhead. Uryū sucked in a breath. The walls were lined with all kinds of Quincy tools. Some he was familiar with: Seele Schneiders, strings of gintō—even a glass case with several zeichen crosses in steel or silver. None of them were as large or weighty as Ryūken's own, but the craftsmanship was obviously remarkable nonetheless.

There were also a few things he'd never seen: zeichen that looked like they were meant to be worn elsewhere on the body, spools of what looked like reika silver wire, and the like. His eye was drawn immediately, however, to a set of armor; it hung on a rack against the back wall. The design was asymmetric, as to be expected of armor designed for archers. At base, it was a long brigandine coat, small metal plates stitched into heavy fabric. One half cut off at the waist; the other continued to the knee. The arms were more heavily-protected, particularly from wrist to elbow; the drawing hand less so.

"Reishi Heisō," Ryūken noted dispassionately. "You can take that set if you want it; it's no good to me."

Uryū observed that it was, indeed, made for a left-handed person; Ryūken was right-hand dominant. That didn't explain why he had it. "Reishi?"

"That's what I said. To anyone with half-decent mastery of their abilities, it should be nearly weightless. It's made from reika materials, so try not to ruin it."

"Why are you giving it to me?" Uryū turned to meet Ryūken's eyes, only to be unsuccessful. It seemed he wouldn't look at him.

Ryūken pushed his glasses up his nose. "As I said, I have no use for it. I have no use for anything in this room, so take what you want. But bring it back—some of these pieces were difficult to acquire."

If they were so difficult to get but useless, why gather them at all? Maybe they were a bequest from his grandfather. Nevertheless…

"Fine." Uryū pressed his lips together, starting towards the case of zeichen before abruptly reversing his direction. "Ryūken."

He paused in the doorway on his way out, glancing back over his shoulder at Uryū.

Bracing himself, Uryū lowered his head and upper half into a brief bow. "For this past month… I am… grateful." When he rose, he caught the flash of an expression he could not read on Ryūken's face, but it disappeared quickly.

"Don't do anything stupid, Uryū." Ryūken turned so he was facing forward again and left the armory.

* * *

"Guys… why aren't Karin-chan and Yuzu-chan with you?"

Rukia knew that Uryū was in the living world without the permission of the Sōtaichō to begin with; he'd told her that much before he left. He'd also said he was going specifically because the Kurosaki twins needed his help, but he hadn't had a lot of time to explain further than that.

But the fact that neither of the twins were with the group was disconcerting.

"You mean you don't know?" Renji looked surprised.

Rangiku and Hitsugaya did not.

"Do not know what?" Byakuya narrowed his eyes slightly at his vice-captain.

Rukia could understand why; Karin _was_ his eighth seat, and maybe a month out from official promotion to sixth seat. He was absolutely awful at expressing emotion, but if nothing else, the sheer amount of time and energy he devoted to his division spoke volumes about how he felt. If something had happened to them and no one had informed him…

When no one else jumped to explain, Rangiku sighed. "Yuzu-chan was kidnapped by the Arrancar," she said quietly. "The same day Iba-san died. Karin-chan's been waiting for a way into Hueco Mundo to try and rescue her."

"The same day Iba… but that was more than a month ago!" Rukia glanced at Renji, hoping there was some kind of mistake or _something_ ; he shook his head slowly. So it was true, then. "How can the Sōtaichō possibly have thought it was acceptable to keep something like that from us? We're her friends!"

Well, Rukia certainly considered her a friend.

"That is likely precisely the reason," Byakuya observed. "But it does not explain why I was not informed, either."

It sure didn't. Rukia crossed her arms over her chest. That was something that was not only important information, but had a direct impact on one of the Sixth's officers. She couldn't think of a single good reason _not_ to tell Byakuya, except that the Sōtaichō didn't think he should know. But why?

"It's a war," Hitsugaya said flatly. "Everything is need to know. Maybe the most senior captains have heard by now, but… he probably didn't want to take the chance that anyone would call for a rescue."

Rukia frowned. It was true: some of the captains were more idealistic than others. Doubtless, there were a few who would think it was a good idea to send a party into Hueco Mundo, even to retrieve one shinigami. _She_ thought they should do it—but Rukia knew she was biased. It was Yuzu—and if Yuzu and Karin were involved, Ishida wasn't far behind. That was three of her friends at risk. One of them a very close friend at that.

"It's still bullshit," Renji put in.

Rukia nodded. She was pretty tired of not really having any idea what was going on. Having to guess at the motives of the senior officers and piece together their strategy wasn't helping. She pushed a sigh out of her nose and glanced back at the Senkaimon. They'd passed through just a minute ago; now they were on their way to a debriefing.

Suddenly, Byakuya paused. "Suppose for a moment that you were given the choice: would you choose to enter Hueco Mundo in pursuit of this goal?"

"Obviously," Renji said immediately.

"Hell yeah," Zaraki added. "I'm itchin' to get in there."

Yachiru nodded. "We should help Zu-chan and Ri-chan and Pencil-kun."

Rangiku glanced at her captain. Hitsugaya crossed his arms.

"If I could choose? …Yes. I'd go."

His vice-captain nodded as well. "Those three… yeah. We should be helping them."

"I'd like to," Iemura replied, "but honestly I think it'd be better if I made sure the captain was aware of everything. The Fourth still needs to prepare for everything ahead."

That was understandable, considering just how important the Fourth's job was. Rukia glanced at her brother, only to find that he was already looking at her for some reason. It took her a few seconds to realize why.

"Me?" she asked, mostly rhetorically. "Of course I would."

"Then I suggest you all pack quickly," said Byakuya, deadpan as ever. "You will not be missed at your debriefing for some time. As I was only instructed to ensure that you made it back through the Senkaimon, my task is finished. I believe I will be going back to the manor for a time. The outdoor staff should be called in for the afternoon—it seems that it may rain."

Rukia's eyes went wide. "Nii-sama."

"I have heard that Hueco Mundo resembles a desert," he observed neutrally. "If I were to travel there, I would go with protection against the sand."

Without another word, Byakuya broke away from the group—heading, as he'd suggested, towards the Kuchiki manor.

"Uhh… what just happened?" Renji raised a hand to scratch his head.

Rukia's face broke into a grin. "Nii-sama's bringing in the outdoor staff. We'll be able to use the family Senkaimon to get back to the living world—without being seen."

"We don't have much time," Hitsugaya added. "Everyone… meet at the Tenth in half an hour."

* * *

As expected, it hadn't taken long at all for Urahara to configure a process for opening a garganta. He'd gone straight to work on it as soon as he'd stepped out of the gate to Hell; apparently crazy genius scientists didn't really need as much sleep as other people. Karin had noticed the looks Yoruichi was shooting him; Karin figured they were somewhere between exasperation and concern.

He _did_ look a little more like a bum than usual, even—Karin didn't want to know what roughly four months in Hell had been like. The day she'd spent down there herself had been more than enough. But he didn't have a chain, so she figured he'd worked out some way to fight at least the physical effects.

Since he wasn't really acting any different than he had the last two times they'd met, she had no idea about any mental effects.

"It's not quite like a Senkaimon," he told them. "You're going to have to navigate with some kind of movement technique before it'll actually put you out in Hueco Mundo. But if you keep moving forward long enough, you'll get there."

A soft metallic clink told her that Uryū had shifted slightly—he wore some kind of light armor under his black cloak. Yorugen was tied on over the armor with his usual sash, but it looked like he had a second belt as well. She couldn't see what was on it—Quincy stuff, maybe. She glanced up at his face; he nodded.

"We're ready," she said. "Go ahead and open it up."

"I hope you weren't planning to leave without us!"

Karin sensed new reiatsu enter the basement at the same time as a familiar voice called down to them. Her lips parted when she felt still more—it looked like almost everyone had come back—with the addition of Rukia.

"Rukia-san?" Uryū was clearly just as confused as she was.

Rukia, Rangiku, Renji, Hitsugaya, Zaraki, and Yachiru all entered the basement, each wearing a tan cloak over their shihakushō. Rukia, at the front of the group, stood with her hands on her hips—most of the others wore expressions ranging from Rangiku's sly smile to Zaraki's bloodthirsty grin. Hitsugaya was frowning slightly—but Karin was so surprised he was even _there_ that it hardly mattered.

"What are you guys doing here?" she asked, shaking her head. "Aren't you going to get in trouble with the Sōtaichō?"

Renji shrugged. "It's not like we were gonna let you go by yourself, birdbrain."

"Or you, Ishida." Rukia lifted her hands from her hips and crossed them over her chest. "When you said the Kurosakis needed your help, you _could_ have been more specific, you know."

Uryū glanced down and to the side. "Sorry," he muttered.

Rukia rolled her eyes, but she didn't press the point. "Well? What are we waiting for? We've got someone to save."

"And some Arrancar to fight," Zaraki added; the bells in his hair jangled as he took a step forward. "So let's go already."

* * *

Kenpachi's path wasn't the steadiest thing he'd ever walked on, but it did the job. The others didn't seem to be having too many problems, either—the Ishida kid wasn't even moving. Some kind of disc or something just propelled him up.

Yachiru was apparently pretty excited about it. "Pencil-kun, what are you doing?"

The kid made a face at being called 'pencil.' Most people weren't that happy about Yachiru's names for them, Kenpachi figured; it wasn't like there was any stopping her. Kenpachi tried to make his reiatsu go forward, but it was honestly a pain in the ass to do anything but attack or defend with it. This was why he didn't bother with kidō or _shunpō_ or that other stuff. It was way easier to tank a hit than try and get way from one.

"It's an instance of _hirenkyaku_ ," Ishida answered.

Kenpachi had never heard of that, but whatever. If it was something shinigami didn't do, maybe it'd be interesting to fight someday. For now, he'd focus on all the Arrancar he was gonna run into. That sounded like a plan.

" _Hirenkyaku_?" Kuchiki's sister knew what it was, obviously. "You mean… you got your Quincy powers back?"

That'd explain it. Kenpachi had pretty much forgotten that the kid was a Quincy. But it made more sense now, since he was a ryoka once, too. He felt the desire for a match go up a bit. The Quincy were supposed to be some kinda big deal or something, right? The old geezer might have mentioned it once. It stuck about as well as the kendo did.

Ishida nodded. "I'll tell you the story some other time. I think we're almost there."

Just as he said it, a point of light showed up ahead of them. Without needing to yap about it, everyone sped up. The point got bigger, until it was an opening, and they jumped through it in twos. There was no way Kenpachi was gonna be anything but first, so he and Yachiru got to the ground before anyone else.

Sadly, they didn't land right in the middle of a bunch of Arrancar or anything. Kenpachi guessed that was fine; he was mostly interested in finding that Grimmjow guy and settling things once and for all. They'd both had a month; it was time to see who was the stronger one.

The scenery was pretty damn boring actually—there was nothing out here but a bunch of sand. It was white sand, but still. Couple pieces of driftwood or whatever. Next to his foot, a lizard with a Hollow hole in its chest ran by.

Well, that was fuckin' weird. He didn't even know lizards could turn into Hollows in the first place.

"Ken-chan, look!"

Yachiru put a hand on either side of his head and tried to rotate it. Swatting her arms away with no real force, Kenpachi turned around with his whole body instead.

"Huh. Figure that's where they are?" Renji landed next to him with a _whump_.

The short captain—Hitsu-something-complicated—crossed his arms. "It's Aizen. Does anyone think he _wouldn't_ be in the huge castle?"

No one argued with that.

"You think they keep Yuzu-chan that close?" That was the Tenth's vice-captain.

Kenpachi swore he'd learned all their names at some point; he was just pretty shitty at remembering anyone he hadn't fought. The minute they crossed blades, though, he'd never forget.

"Depends on why they took her," Ishida said. "But probably. Seems like the best place to start looking, anyway."

And the best place to start fighting, Kenpachi figured. He could get behind this plan.

* * *

 _Term Dictionary_ :

 _Zeichen_ – 滅却印 – The kanji are "Destruction Mark;" the German is simply "Mark." Refers to the pentacle or five-pointed star design of most (but not all) Quincy crosses. In particular, Uryū uses a more traditional "cross" shape in the early days of the manga/anime, but eventually switches to the zeichen-style cross. In CT-verse, he's had a basic pentacle one since TBE.

 _Reishi Heisō_ – 霊子兵装 – "Spirit-Particle War Garb." In keeping with my personal headcanon that the Quincy are really good craftsmen/smiths, this is happening. It appears partially in like two panels in "Everything but the Rain" when Ryūken wears it, but we never get anything close to a bodyshot. So I'm blending Uryū's Letzt Stil armor with a medieval brigandine-type coat (of the many-small-metal-plates variety, if you want to google image it). It seemed logical since most Quincy uniforms/armor/motifs are distinctly European in influence and style. Plus, I think the armor over a shihakushō is a really good visual representation of his particular blending of identities. I'll let you guys guess how Ryūken ended up with a left-handed set when he is not left-handed himself.

* * *

So… they finally made it. Which means… hoo boy, I get to write an absolute glut of fight scenes. No promises about speed on that; I've been finding them more challenging to get through recently, but I'll do my best. Also, it might be another day or two. Saturday (today) is my birthday, so… there's a high probability I'll be dragged away from my computer at some point. :)

Also, I'm really really behind on my review responses. I know that, and I apologize. So basically, I'm gonna hit reset: if you have a question you wanted answered and I didn't get to it, please ask again. If there isn't an actual question in your review, I can't promise I'll reply, but I'll try my best!


	12. Chapter Twelve: An Eye for an Eye

.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Twelve: An Eye for an Eye

* * *

"Good evening, lady and gentlemen of the Espada." Sōsuke, with Gin and Kaname in tow, descended the short staircase to the head of the long table. It stretched out away from him, allowing him a view of all the faces present.

Deliberately, he scanned each of them as he descended. "We are under attack." He made the announcement softly, as its trivial nature demanded. Of course… it was not quite so trivial as it could have been.

For one, it was ahead of schedule. He'd not yet detected Kisuke Urahara's return to the world of the living; admittedly, the exact size and strength of the force was above his initial estimation as well. But in the end, it wouldn't make a difference. His plans were already in motion; inertia alone would push them far enough forward for completion. There were simply no obstacles weighty enough to stop them.

"But first… shall we have some tea?"

He raised a hand, making an idle gesture to signal to the servant Arrancar stationed at the door. Settling into the chair at the head of the table, he folded his hands in front of his mouth, propping his elbows on the black stone beneath them. It was interesting, reading their faces.

The ten men and one woman sitting around the table had a range of responses to choose from—from Yammy's wide grin all the way down to Starrk's utter disinterest. Though… he wondered, now, if that disinterest would remain when the circumstances of the invasion became clear.

Sōsuke was served first; though he usually didn't bother, he stirred a small amount of sugar into his tea. Just a little touch of something sweet—that seemed apropos for the moment. Eventually, refreshments made their way around to everyone; Sōsuke allowed himself a small smile when Anzparrejar pulled down his mask to drink it. So that was the form he'd taken, then—how interesting.

"Now then… please listen while you drink." Sōsuke took a slow sip himself. This wasn't his usual flavor, but it did have a certain fragrance to it that he could appreciate. Of more interest was observing the reactions of the Primera and the Cuarta.

They did not disappoint. Starrk took a whiff of it and paused, cup halfway to his mouth, before slowly setting it back down again. Ulquiorra stared flatly at the steam curling from the top of the cup; he didn't so much as touch it.

A shame. Lotus tea was a luxury item in any world, this one included.

"Kaname," Sōsuke said, not turning his head. "Visuals, please."

He did appreciate a certain kind of irony, after all.

"Yes, sir." Kaname gripped a lever in the wall and pulled it with a soft _click_.

At the center of the table, the surface layer peeled back, uncovering a projection screen. A column of pale light flickered into existence; images resolved within it. A group of shinigami, running across the endless white sand of Hueco Mundo.

Leaning on one hand, Sōsuke explained. "There are a total of eight intruders." The screen zoomed in on each of them in turn, freezing the frame and projecting a list of related statistical information: height, weight, identifying markers, division and rank, and known abilities. For some, there was a great deal more than others—after all, Sōsuke, Kaname, and Gin had known many of these people personally for a long time.

"The leader of the team, insofar as they have one, is the captain of the Tenth Division—Tōshirō Hitsugaya." The frame froze on the youngest Gotei taichō's face, text cascading down the screen in luminous blue.

"That runt?" Yammy looked quite skeptical.

"Indeed," Sōsuke replied. "With him are Captain Zaraki of the Eleventh Division—" he paused there for Grimmjow's inevitable reaction.

Interestingly, though the Sexta was clearly more interested in the proceedings than he had been a few seconds prior, he did not make a scene. Restraint was certainly an unusual trait to find in him; Sōsuke suppressed a frown.

"—as well as both of their vice-captains, Yachiru Kusajishi and Rangiku Matsumoto."

Actually, dealing with the particular conundrum _she_ presented at this stage rather than later should expedite things nicely. Slightly behind and to the right of him, Gin remained completely still. It would have fooled anyone else, perhaps.

"There is new data on Renji-Abarai-fukutaichō; if you haven't examined the information since it was first presented, you may wish to refresh your knowledge." The color that spilled over the surface in front of him changed from being predominantly red to mostly dark—Sōsuke glanced across the projection, letting his eyes fall on Aaroniero. "As expected, Rukia Kuchiki is here as well."

There was considerably less information on the last two—the screen captured a single still image for both of them, sparse lines of data appearing below. "And here, we have our most interesting invaders. Karin Kurosaki is the twin sister of our present houseguest. It is established that her zanpakutō is fire-type, able to enhance both her physical attacks and her movement speed. Note that the numerical values assigned to her battle data are speculative—she's been a busy girl in the past month."

He knew Urahara had a method of bankai training that took only three days—there was no reason to suppose that, in his absence, Shihōin had _not_ used it on Shiba's daughter.

The last entry was one that Sōsuke personally found the most intriguing. Here, after all, was an impossibility he had _not_ had a hand in creating; not directly, anyway. "The last one is Uryū Ishida. As you can see, no battle data is included for him—I suggest that, should initiating combat with him prove necessary, you proceed with caution."

The data would be gathered in time, of course; that was part of the point of this little exercise.

"Now, as you can see, there are only eight of them. However… it would be unwise to underestimate them." He could tell from some of the looks at the table that it would occur no matter what he said. But he could hardly fault them for what was in their natures.

"Nonetheless… there is no need to make a fuss. Each of you is to return to your chambers and act normally. Do not be haughty; do not get impatient. Just sit and wait for them." He paused for effect, allowing his smile to grow slightly.

"After all… even if something should happen… as long as you walk with me, there shall be no enemies in our way."

* * *

Yuzu felt Ulquiorra's approach well in advance of him actually appearing in her doorway. At the moment, however, she found herself quite unable to react to it much. Instead, she remained still, seated against one of the arms of her sofa; her legs were pulled up under her and folded to the side. She propped her chin in her hand against the armrest and stared out the window.

Something was wrong. Well, _comparatively_ wrong, anyway.

Aizen had been different in their last encounter. Specifically at the end—he'd seemed more… brusque? For someone who wore his shroud of politeness as if it were an extra layer of superiority and control, she could only conclude that something had disturbed that tranquility of his. Had he, perhaps, caught on to what she was doing?

Wouldn't he already have known?

She chewed her lower lip, rolling it between her teeth and biting down. The dull pressure registered distantly in the back of her mind; she ignored it. But if he knew, why be bothered _now_? Maybe it had nothing to do with her—and yet he didn't seem the type to let on if something _else_ was bothering him. Maybe she'd imagined it. After all, the difference had been only slight; it could be that she was conjuring changes where none really existed.

And yet she could not shake the sense that her time here grew short.

A soft scuff interrupted her circling thoughts. Yuzu blinked; the room around her came back into focus. Turning her head, she spotted Ulquiorra. He didn't look any different from usual, really—even his posture was the same, down to the hands in his pockets and the perfect straightness of his spine.

"What happened?" she asked, standing slowly. Something was off.

He shifted his eyes from her to the window and back again. "Your friends have come," he said tonelessly.

Yuzu sucked in a breath. Her friends… he must mean…

"Is it a first offensive?" she asked quietly. "Or a… rescue?"

"They are here for you. Because of you."

Her knees buckled. Yuzu sank to the floor. A bone-deep shake rattled her limbs, shuddering down her spine. They were here. They were really _here_. She blinked several times, trying to clear her eyes; despite her best efforts, her hands blurred in her vision. Curling her fingers into the white rug, she bit the inside of her cheek.

One drop darkened the rug next to her fist. Then came another, and a third.

"This upsets you?"

The toe of a black tabi entered her visual field; Ulquiorra had stepped closer. Yuzu shook her head, raising one of her hands to her mouth to smother a sob. With great effort, she pushed herself back into seiza. Turning her eyes up to meet his, she shook her head again.

"N-no," she managed. "I'm actually… I'm so relieved. I'm so happy."

They'd come. They were really here. Karin and everyone. They were all alive.

For a month, she'd had no idea what was going on. Whether more Arrancar had been sent into Karakura; whether anyone else had died. But if they were here, then they were alive. Yuzu dared to hope that she might just survive as well.

Ulquiorra's brow furrowed faintly—quite an expression, for him. "Do you not understand what this means? We will be deployed against them. We will do battle. Death is the only result."

Yuzu gave him a watery, tremulous smile, lowering her hand away from her face. "Is that concern I hear, Ulquiorra-san?"

To her utter shock, he averted his eyes from her and did not respond.

She'd expected an immediate denial; perhaps a redoubling of his cold, impartial tones. A month had given her time to learn to read even the subtlest cues of his behavior—to begin to translate them into the feelings he claimed he did not have. Next to the difficulty of that, this was downright obvious confirmation.

Her smile faded; slowly, the tears ceased flowing. "I thought you didn't see a reason to be concerned with death," she said, tilting her head.

He'd been quite clear about it—the human need to remain alive was just as much a mystery to him as any other strong feeling or drive. She'd thought that strange, and told him so; for how else would he have come to be so strong but through the desire for strength and life? Hollows did not escape death and consumption by mere _accident_ ; not in a place like Hueco Mundo.

"I didn't." There was a long pause. "But you do."

Yuzu swallowed thickly, then nodded. "Yes."

"Aizen intends to kill you."

Yuzu inhaled deeply. She supposed he must mean soon; it had been obvious to her from the very beginning that he would kill her eventually. "He told you that?"

"Indirectly. He implied that what is keeping you alive now is our compliance with his will."

That _did_ surprise her. "He… threatened you with… my death?" It took a little reading between the lines of his words, but she thought that was what he meant.

Ulquiorra shifted his eyes back to her. "Yes. He will kill you anyway, but if we do not comply, he will do so sooner. I believe… that is the kind of thing that makes a difference, is it not?"

Yuzu licked her lips, parsing her words carefully. "Does it… does it make a difference to you?"

There was a long pause. She counted her heartbeats; a full thirty of them passed before he replied.

"…Yes."

She exhaled; only then did she notice she'd been holding her breath the whole time. Yuzu felt her shoulders slacken; the smile came easier this time. "I don't know what's going to happen here," she said softly. "It's confusing and intricate and overwhelming, but… no matter how we end up…"

She extended her hand into the space between them, offering it to him. "Thank you, for that. For this. I know it would have been easier if things were some other way."

For a moment, he simply stared at her proffered hand. He blinked once, slowly. But then with a soft rustle, he removed his own from a pocket. He stopped an inch short of hers; she remained perfectly still.

She saw his eyes narrow—just a fraction—and he closed the remaining distance. The skin of his hand was cool and dry, almost like rice paper. Certainly not what she expected of hierro. She wrapped her fingers around it and used it to pull herself to her feet.

"I'm going to be okay, you know," she told him. "And so are you. You'll see."

"I do not know where such assurance stems from," he replied.

Yuzu squeezed his hand slightly before she let it go. She wiped a few tear-tracks from her cheeks with the heel of her other hand, blinking several times to try and dry her laden eyelashes. Her mouth turned up softly.

"Yes you do."

* * *

"Just how big _is_ this damn place?"

Renji's sense of scale was completely useless, apparently. He'd figured, based on the size of the castle and where they were standing, that it would take them a few minutes in shunpō to reach it. But it had been more than fifteen, and while the castle just kept _growing_ in his vision, they didn't seem to be getting any closer to the damn thing.

"I think it might be more of a city than a castle," Ishida said, frowning. "Do you think Aizen really built it, or was it here before him?"

"Does it matter?" Renji thought the more important part was getting into it.

Ishida shrugged. "I think we'll be to the wall in another ten minutes. Does anyone see a gate?"

"We must have landed on the wrong side," Hitsugaya said. "Probably it would be quicker just to break through—the walls don't seem to be made of sekkiseki."

"Most direct path in, huh?" It was probably for the best—who knew how long it would actually take them to find a gate? And that assumed there was one, and that getting into it would be easier than breaking down a wall in the first place. None of that seemed like a guarantee to him.

By the time they actually reached the wall, Renji had drawn Zabimaru. He and Captain Zaraki were most suited for this kind of thing, most likely. Releasing his zanpakutō, he cracked his neck to either side and braced Zabimaru with both hands.

Between them, they made short work of it; a section of the stone crumbled away. Everyone took a few steps back while the dust settled. When they were able to climb in, they found themselves in a big room with a dome for a ceiling—it must have been built right along the outside wall.

"Four doorways."

Renji glanced over, following Rukia's eyes until his own settled on the openings she was talking about. He frowned; splitting up this early wasn't the best plan, but it'd have to do.

"We should take them in teams of two, right?" He looked to Hitsugaya. Technically, the captain was in charge of the operation, after all.

"Why?" Ishida protested. "Shouldn't we all stay together? We have no idea what we're going to encounter in there; it makes sense to ensure that we can deal with it."

Renji frowned. "You think we can't handle it in teams?" he asked, raising an eyebrow.

"That's not what he said, dumbass," Karin replied, crossing her arms. "Uryū has a point. Whether we _could_ handle whatever we ran into is too hard to guess. What if a bunch of 'em are all having lunch or something in the same room? What then?"

Hitsugaya pinched the bridge of his nose between his thumb and first finger. "We shouldn't ruin the advantage of speed," he pointed out. "It might be the only one we have—Zaraki!"

The other captain waved a hand, continuing towards the first door. "While you people stand around arguing, I'm gonna go fight some stuff. See ya later." He disappeared into the leftmost doorway, Yachiru on his shoulder.

"Idiot," Hitsugaya muttered. "He does have one thing right, however: if we spend too long sweeping all these hallways together, we give them more time to prepare. Even a few minutes may make the difference, when these people are involved. We'll split up, and try to find each other again as soon as possible."

Renji nodded. It seemed like the best idea to him.

"Matsumoto and I will take the center-left. Abarai and Kuchiki, you take far right. Ishida, Kurosaki, center right."

Ishida looked like he wanted to argue, still, but Karin grabbed his cloak near his elbow and shook her head.

"Leave it," she said. "We'll manage."

"Fine." He pushed a breath out of his nose and turned to Rukia and Renji. "Be careful."

Renji thought there wasn't much point in saying that, but he nodded anyway. Rukia did too, then smiled.

"We'll be fine. See you in a little while."

* * *

It turned out that waiting for her friends to reach the central part of Las Noches wasn't that different from all the other waiting around she'd been doing.

Though it might not have been the most tactically-sound decision, she'd sought out Starrk as soon as Ulquiorra had left—summoned by Aizen, no doubt. She still had no idea how this was going to work out; it was clear that even if she'd succeeded in making herself some friends, Aizen had managed to make that work just as effectively for him as if she hadn't. Where before they'd done as he told them for their own reasons, now…

Now they did as he said at least partly for the sake of keeping her alive. Or so she'd inferred.

It was a bittersweet realization. Sweet because, of course, they were trying to keep her alive. The bitter part was that it probably wouldn't make much difference in the end. Still… every extra second she was here was another second Karin and the others could use to take a step forward. Perhaps… Yuzu allowed herself to hope it would all work out in the end. Somehow.

"You okay?"

Starrk's voice startled her; she shook herself out of it.

"I… yes. I'm just starting to… overthink, maybe. Trying to figure out what to do." At this point, there was no use hiding the fact that she was strategizing.

He sighed, rubbing lazily at the back of his neck. "I don't blame you. I dunno what Ulquiorra's doing, but… I think it's best for me if I just act normal until it seems better not to. There's a chance we'll still have to fight your friends, you know."

Yuzu nodded. "I do. And… and I know what Aizen will probably do to you if you refuse. I just… I feel like I was trying to find a way out of all this, and ended up painting you into a corner with me." It was incredibly frustrating; Yuzu's hands curled into her hakama.

Starrk studied her for a while. "You didn't do anything we didn't let you do," he said slowly. "Maybe the others think differently, but if you ask me… a month of not being lonely for once in my life was worth not really knowing what happens next."

She chewed her lip. "I don't know how long I would have made it, without you," she confessed. "Just… just having someone to talk to. Someone I wasn't afraid of." Yuzu had no doubt that Starrk was strong, but of all the Espada, he was the one who frightened her the least—simply because, from the beginning, he'd had a sense of decency about him.

He reached over, laying a hand on her head. "You'd have made it. You have deep roots, kid. Strong ones. Don't let anyone tell you differently. Especially not Aizen."

"Why do you think…" she paused, pursing her lips. "Why do you think he managed to gather so many followers? I just don't understand what about his plan would be so appealing to Arrancar, really."

Starrk considered that, frowning slightly. "Everyone had a different reason, I think," he replied. "He knew enough about each of us to offer what we wanted, whether or not he could really provide it. But deep down? …Probably fear."

"Fear?"

He dipped his chin. "I doubt most of us had ever met anyone stronger than we were. Hueco Mundo is a pretty cutthroat kind of place—you eat or get eaten here. Most Adjuchas and Vasto Lordes don't have to worry about being eaten so much, but… that kind of primal instinct doesn't just go away. Him, though…" Starrk heaved a deep sigh. "He's stronger than any of us, and I think only Baraggan didn't know that right away."

"And if that was true… your options were follow or be eaten?"

"Yeah. Doesn't sound too nice, which is why it got covered in different pretty words for everyone. But at the bottom… it was fear."

"But…" Yuzu clasped her hands together, leaning back against the wall they shared. "If that's true, then… aren't you still afraid?"

"Of course I am," he said bluntly. "But I know someone else who's afraid… and even after a month of being worn down and lonely and scared so bad she hardly sleeps… she puts up a hell of a fight." One side of his mouth quirked for just a second.

"She got me thinking maybe I could, too."

Yuzu's face colored; before she could properly respond, though, a new reiatsu signature entered the area, approaching fast.

Grimmjow didn't bother to knock before throwing open the door. He spared Starrk only a cursory glance before his eyes landed on her.

"Hey. You want out of here, right?"

It took Yuzu a couple of seconds to process that. "I… yes." Ideally at a time that made sense based on the flow of things, but beggars couldn't really be choosers, as they said.

"Good. I'll make you a deal. Follow me, heal someone when I tell you to, and then when I'm done fighting him I'll open you a garganta myself. How's that?"

"Are you—are you sure?" She blinked at him, pushing off the wall.

He snorted. "Would I have said it if I wasn't?"

She supposed not.

Yuzu turned to Starrk, but he was already nodding. "Don't worry about me. I didn't see anything. I was just here, taking a nap." He waved a hand idly, gesturing her forward with it.

She was halfway to the door when he called out to her.

"Yuzu."

Her steps hitched; she turned halfway back. He regarded her with a solemn face, eyes half-lidded and mouth downturned.

"If I don't see you again… thanks."

* * *

Karin and Uryū ran side-by-side down the hallway they'd been assigned—not a hard thing to do, since it was easily wide enough for four.

"Can you feel anything?" she asked him; his sense for reiatsu had a better range than hers. She was registering mostly nothing, which was annoying. It was like everything was suppressed by something—or blended together. She couldn't make sense of it.

He glanced down at her from the corner of his eye. "Sort of," he said between deep, steady breaths. "There's something ahead, but I'm not quite certain what it is."

"Why can't we sense things right, anyway? Is it something to do with this being Hueco Mundo?" Normally, she could pick Yuzu out pretty much anywhere—here, she couldn't feel her at all. Karin refused to let herself think that this was because Yuzu wasn't there to be sensed. Something else had to be going on.

Uryū pursed his lips, leading them around a corner when they reached an intersection. "I think… I think what's blocking us might be Aizen's reiatsu. I've only felt it once, and it wasn't quite like this, but it's close."

Karin scowled. "You mean he's so strong we can't feel anyone else?" She couldn't even get her head around how strong that had to be, especially knowing how tough the Espada were themselves.

"I really hope not," Uryū replied.

An open doorway at the end of the hall led them into a really big, circular room. There were a lot of pillars in it, stretching from the floor almost to the ceiling. Like everything else in this damn place, all of it—walls, floor, ceiling, pillars—was stark white, almost painful to look at for too long. Uryū stopped when they reached the first pillar, pushing his glasses up his nose. He folded a hand into his cloak; she heard the slight click as he placed a hand on Yorugen's hilt.

"Something's here," he warned her.

She didn't need any more guarantee than that; Karin laid a palm on Hisaku's tsuka, wrapping her fingers loosely around the red fabric there.

A glint in the corner of her eye was the only warning she had.

"Uryū!" Karin jumped clear; a metal disc of some sort hit the ground where they'd been standing not a moment before. It retracted not a moment later; Karin's eyes followed it to the top of one of the pillars in the room. "Up there." She jerked her chin at the silhouette just barely visible on the column.

"There's more," he said, drawing Yorugen with a rasp.

"Cirucci!" boomed a deep voice. "You were supposed to wait so I could make my entrance!"

"Shut up, Dordoni. My house, my rules." If Karin had to guess, the woman's voice belonged to the one who'd attacked.

In a different direction from the first two, someone grunted. A thud came from the left; a big guy with a dark orange afro landed on the ground. "Surprise is for cowards, anyway. A fair fight is best."

Karin glanced at Uryū. He pressed his mouth into a straight line and nodded.

"If you're gonna come at us all at once, you better get started," Karin said, drawing Hisaku. "Or we're gonna come for you instead."

* * *

Rukia was pretty sure she and Renji had lucked out in terms of paths to follow: it was only about ten minutes before they came upon stairs leading up. There was a rectangle of light near the upper landing; if they could make it out there, they might have a better idea of what they were looking at.

Renji led the way up. Rukia matched pace behind him, her arms tucked back into her cloak. They emerged, blinking, into what must have been the interior of the castle dome, and yet….

"Daytime?" Rukia drew to a stop; Renji in front of her did as well. "And no dome…"

"Time distortion?" he asked, tipping his head up to take in the sunshine and soft clouds.

That would explain the change in the sky, _maybe_ , but definitely not the complete lack of the dome they'd seen from the outside. This whole place was supposed to be enclosed. Unless they'd taken a wrong turn somewhere and wound up outside of it again. The stairs seemed to have put them out on some kind of raised wall—smaller buildings lay below. Rukia glanced down over the side, deciding that there were too many roofs to count.

Why such a large place? There weren't _that_ many Arrancar, were there? Did Aizen intend some other use for it?

"Hey Rukia—look at that." Renji pointed.

Rukia followed the direction of his hand. Her eyes rounded in surprise. "A—a sky? Is that a sky coming out of a building?" It certainly appeared to be. It looked like a watchtower on the wall, except that the surface was oddly concave, and more clouds seemed to drift sideways over it. Surely it must be some form of illusion, but—

"Would you like me to tell you?"

Rukia and Renji both whipped around. Behind them—not more than two feet from her—stood an Arrancar. His mask was strangely elongated, with eight holes arranged two by four that did nothing to hint at the face beneath. A tall collar fringed it, arranged in ruffles that continued down into his overcoat. He stood with hands folded together; his tone was exceedingly calm and almost… familiar, somehow?

"Wha—"

He disappeared from her vision, reappearing at the far end of the wall, right next to the tower with the sky on it.

"Follow," he said simply.

"Why should we?" Renji asked, but the figure was already disappearing into the door.

"Renji," Rukia said firmly. "You keep going. If this is a trap or a distraction, we can't both get caught in it. I'll see if there's anything to it." She couldn't help but wonder—that vague sense of familiarity she felt…

He looked at her skeptically for a second, but she knew his first instinct was always to trust his companions. It was one of the best things about him—and she was counting on it. Eventually, he nodded.

"Yeah, okay," he agreed. "But watch yourself in there, Rukia."

"I will."

Renji hopped off the wall, no doubt to begin the search for another way forward. Rukia hopped into a run, pursuing the Arrancar inside the tower. The open doorway she stepped through provided the only illumination in what was otherwise an extremely dark chamber—it was colder than the outside, too. Rukia shivered slightly under her cloak—more from the lack of light than the chill.

"Ahh… I can finally relax."

The return of the Arrancar's voice was accompanied by a slight grinding, as the door behind her closed. Rukia's hand immediately went to the hilt of her zanpakutō; she'd be vulnerable in the time it took her eyes to adjust.

"Sorry," he continued; the tone of it was almost… jocular? It only seemed more familiar than it should, now. "For a very long time, I haven't been good with that whole sunlight thing."

Her vision was coming back; he was easier to see because of all the white he wore. His shoulders moved; she thought it might have been a shrug.

"The sun won't reach inside here, though. So I'll remove my mask and greet you." Raising his hand to the bottom of it, he hooked a couple of fingers under its chin. "I'm Aaroniero Arruruerie, the Novena Espada."

The mask came away from his face; Rukia gasped.

It couldn't be.

He was dead—there was no way it…

But his face was so achingly familiar. She'd know it anywhere.

"K-Kaien-sama?"

* * *

 _Notes_ : Well… that one took a while. :/ But anyway, here we are with the beginning of the Hueco Mundo invasion. I feel like Rukia _has_ to fight Aaroniero—it's such a personal thing for her, and the canon divergence here hasn't really changed that much. Karin and Uryū have all three of the Privaron Espada. As for what Renji, Kenpachi and Yachiru, and Tōshirō and Rangiku run into, well… you'll see. (Though if I'm doing my job right, Kenpachi's opponent should be pretty obvious).

Anyway, I hope the changes here all seem to work; particularly those in the three Espada Yuzu's had decent amounts of contact with. I wanted the character development to seem reasonable; I'd be interested to know what you think went right or wrong there (or anywhere, really).


	13. Chapter Thirteen: Don't Come Around

.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Thirteen: Don't Come Around Tonight

* * *

Most of these buildings didn't really seem to have much in them. Renji had opened a few doors to be sure, but nothing stuck out as important. So now he was left trying to pinpoint and track any significant reiatsu he could find; it was harder than it should have been for some reason.

Still, with any fortress, the important stuff was near the middle; so he kept heading in that direction, hoping to find some sign of Yuzu, or even any of the others. Most likely, they'd been held up by Arrancar; there weren't any out here, though.

Eventually, Renji detected a bunch of reiatsu signatures close together. Figuring it was probably a better chance than anything else he'd come across anytime soon, he turned and adjusted his path to meet it. It was coming from somewhere below him and to the north; just ahead, a larger structure stood over all the little ones around it. It had a dome roof, and from the looks of it, only one entrance.

Would it really be that straightforward?

He decided it couldn't hurt to try, landing in front of the door with a hand on Zabimaru. Deciding to release the sword _before_ entering, he muttered the command for shikai and pushed the door inward with his free hand.

The lights immediately reminded him of the Fourth—clinical, or something like that. Too bright for most ordinary places, anyway. Renji had to blink to adjust to it. There weren't really any _features_ in the room, either—which just made it worse. The floor was some kind of tile, and everything else was the same stone everything in the place seemed to be made of. Had Aizen decided he had something against color, or what?

Next to his surroundings, Renji guessed he was probably downright offensive—what with his black shihakushō, black tattoos, and bright red hair. He was pretty used to that feeling, though—it didn't bother him anymore.

Renji narrowed his eyes. This was weird—it seemed like there was no one in here. Taking a few steps forward, he looked up at the dome ceiling. No sign of anything up there. Maybe—

The ground gave out from underneath him, throwing him forward and down through a huge hole in the floor. How had he not seen that?!

He landed in a heap of limbs and a cloud of stone dust. Inhaling, he accidently sucked some of it into his lungs. With several coughs to clear it out, he pushed himself to his feet, wiping at his mouth with the back of his hand.

This underground room was bigger than the other one—and a whole lot deeper. The ceiling was ribbed this time, like he'd been swallowed by some huge whale or something. He didn't have the chance to really notice anything else before high-pitched laughter drew his attention.

"What the hell…?"

"I set out quite a few different traps, but to think someone would get caught in the simplest of them…" From the dust appeared a figure—an Arrancar. His hair was the same weird pink color as Yachiru's; it looked like his mask fragments had given him glasses or something.

"Oops… my apologies." He paused. "Maybe I should have introduced myself first. I will say it only once, so I hope you are able to remember. I am the Octava Espada—Szyelaporro Granz." His voice had a weird tone to it—it went up and down too often.

"Octava, huh?" Renji didn't waste any more time with talking. If this guy was really the eighth of the Espada, he was damn dangerous and needed to be dealt with—the sooner the better.

"…Bankai."

* * *

"Daiguren Hyorinmaru."

Tōshirō felt no inclination to keep much in reserve at the moment—any fight here could be their last if they were too slow to use the advantages available to them. Already, this Zommari—the Séptima Espada, he'd claimed—had proven to be a vexing foe. He was faster than either Tōshirō or Rangiku, and very difficult to hit.

Which wouldn't make a bit of difference if he were frozen solid. " _Guncho Tsurara_!"

Flinging water from Hyōrinmaru's edge, he froze it solid, the added heft of the ice daggers accelerating them in midair. They thudded into Zommari—most were deflected or broken by his hierro, but several struck true.

A cloud of ash followed his attack in; several new thin lines of blood formed when Matsumoto slashed her empty hilt. Was this really—

Tōshirō's eyes went wide. "Matsumoto!"

But the warning was a second too late. Zommari, apparently completely unharmed, materialized behind her. With a heavy blow, he struck Matsumoto's spine, sending her careening into a wall. The impact fractured the stone, kicking up a cloud of dust and debris. Matsumoto staggered backwards, holding her right side with her left arm. Her lip was cut and bleeding freely; one of her eyes closed against the flow of blood from a gash on her temple.

Tōshirō nearly met the same fate—he lost track of Zommari for a second. Taking his best guess, he threw himself forward into a roll. A deep whistle disturbed the air where his head had been. Zommari had missed him by inches. But how—he'd been mangled and bleeding not two seconds ago, so—

"My _sonído_ is the fastest of those belonging to the Espada," he said. Apparently he was fine waiting for the two of them to pick themselves up and face him again. "So fast that it produces afterimages indistinguishable from me."

Clones that _bled_ , apparently. All the more reason to just ice everything over, but… the fact that they were indoors and underground severely limited Tōshirō's most powerful abilities. Still… maybe there was some way he and Matsumoto together could slow him down long enough to hit him.

Slinging an arc of ice, Tōshirō tried to catch Zommari's feet. The Espada simply disappeared again.

" _Bakudo #61: Rikujōkōrō!_ "

Matsumoto succeeded where he'd failed, correctly predicting that Zommari would jump clear of his attack and aiming hers for where he landed. The first beam of light _almost_ missed—but Zommari was stopped cold by it, allowing the other two to cross and reinforce the binding.

Already, though, the light rods of the spell wavered; it wouldn't hold for long. Tōshirō darted forward, bringing Hyōrinmaru around for a thrust instead of a slash. The blade parted Zommari's hierro; the ice that grew to encase his body was the real victory, however.

Or rather, it should have been.

A hard blow cracked across the back of Tōshirō's head; splitting pain shot from his crown to his temples and his vision flickered. Losing control of his flight, he dropped like a stone.

* * *

"Explain to me how it is that two captains, four vice-captains, an eighth-seat, and a rogue tenth seat all managed to get into Hueco Mundo for an unauthorized mission in the middle of a war, and none of you saw fit to report this in a timely manner!"

No one answered.

Genryūsai knew, of course, why this was. They hadn't reported it because they hadn't wanted him to stop it. And there were too many culprits: Shunsui, Jūshirō—both of his apprentices were deeper in this than nearly anyone else. It had their fingerprints all over it. As did anything that brought him trouble, it seemed.

Unohana would have known; her third seat was the only officer who _hadn't_ immediately returned to the living world after being dragged back to Soul Society. He knew _she_ defied the intent of his commands because she disagreed with his strategy; doubtless she saw something useful in forcing this.

Kuchiki might have surprised him the most—defiance was unlike that boy.

Zaraki had always been a loose cannon, ready to fire. The fool. Some things could not be overcome with sheer force—particularly not when that sheer force was yet unrefined.

Hitsugaya was scarcely a child. Perhaps it was his own fault that he'd failed to account for _that._

All in all, it left Genryūsai with a very small inventory of captains that were _not_ apparently confident that they could do his job better than he could. In that moment, he felt very old, indeed, pitted like this against that reckless confidence and self-assurance that was the hallmark of youth. For though he made certain that the opposite appeared to be true, Genryūsai was, in fact, sure of very few things at all.

But one of those things was that they had left him with no choice but to adapt his strategy to their foolhardy machinations. After that, it would be a matter of pitting their strength against whatever Aizen had mustered. Perhaps then, their cockiness would do them some credit.

His fingers, old and gnarled, curled into the equally-weathered wood of Ryūjin Jakka's staff. His scars had begun to ache—something he'd not felt in a thousand years.

"Unohana-taichō: prepare the Special Relief Teams for deployment. Ensure that they are left under effective command. Yourself and one other officer of your division are to make preparations to be sent into Hueco Mundo."

Unohana dipped her head; he did not miss the faint glimmer of satisfaction in her dark eyes. Beneath his mustache, Genryūsai frowned a centimeter deeper.

"As you cannot seem to keep track of either your division members or your family members, Kuchiki-taichō, you will accompany her. Perhaps this time they will prove easier to retrieve."

"Yes, Sōtaichō."

"I believe I should go as well," Kurotsuchi said, stepping slightly out of line to make eye contact. "There may be valuable information to be gained; besides that, someone in there will need to be capable of opening a garganta."

"Very well," Genryūsai said. "You and your fukutaichō will also go." Here, he paused. He could afford to lose no more firepower. But there was one obvious resource as yet left untapped.

"Suí-Fēng-taichō. Have the Onmitsukidō locate Isshin Kurosaki and bring him here."

She frowned briefly, but nodded. "Yes, sir."

He detested the thought of dividing his forces this much; at the very least, however, he would be forcing that brat Aizen to do the same. "Shunsui, Jūshirō, remain here. The rest of you are dismissed. All divisions are to immediately move to active status in preparation for deployment and defense of the Seireitei."

Now… it seemed he needed to contact Kisuke Urahara.

* * *

Nanao heaved a sigh, sitting back slightly in her chair. Her brush remained between her fingers—she needed it yet. Her eyes wandered wistfully to the book on the corner of her desk; she was only about halfway through, and was very interested in how the rest of the story would go.

But unfortunately, duty made its demands. Nanao always obliged.

She'd been spoiled by three years with a functional tenth seat—Ishida always did his paperwork on time; she also suspected that he did most of the work for Enjōji as well. The handwriting was conspicuously similar; she knew Enjōji had a much looser, larger scrawl.

As she'd done extra work for years prior to her promotion, she chose to make a mental note of it, but not mention it.

She bent forward, intent on resuming her path through the stack of forms, when she felt her taichō's reiatsu appear on the roof. The captains' meeting must be over, though it was unusual for him to return to the office after one of those. She'd expected to have to go drag him away from the Thirteenth at some point that evening.

Much to her surprise, he swung in through a window not a moment later. Well—the unconventional entrance was hardly shocking. Rather, he'd entered the office of his own volition; _that_ was quite irregular.

Nanao suppressed a prim remark on his presence when she caught sight of the expression on his face. Kyōraku-taichō was rarely serious about anything. Especially the things he _should_ take seriously. That he wasn't smiling at all immediately had her on edge. Not even the fact that he slid one on right afterwards put her at ease.

"Good morning, Nanao-chan." He pulled his chair away from his desk and to the side, so that when he sat in it, he faced her.

"It's three in the afternoon, captain," she replied crisply, subsuming her concern in the usual way.

His smile widened; she pretended to ignore him in favor of her paperwork. If he had something to tell her, he'd get to it in his own time. It was basically impossible to hurry the captain. She made a point of trying only infrequently—Nanao had learned early on that this increased her chances of success.

For a while, the intermittent rasp of her brush over paper was the only sound in the office. Given his relative size compared to other people, Kyōraku-taichō was remarkably capable of being quiet. But she could feel him watching her, and so she knew that he was not dozing as he often did. The scrutiny made her slightly uncomfortable; Nanao took a mental inventory of herself. Appearance, posture, uniform—everything was as it should be.

If this was some new form of torment, she might prefer that he return to ridiculous and overt declarations of affection.

When she started to fidget, Nanao pushed a sharp breath out of her nose and rounded to glare at him. "Is there something you wanted, Kyōraku-taichō?"

He'd leaned sideways against his messy desk, chin in hand. She wasn't wrong—he was looking right at her.

"Nanao-chan is all business today," he remarked casually. "It's good to relax sometimes, too, you know."

Nanao compressed her mouth into a tight line. "Sir, I am like this _every_ day. If anyone is acting oddly, it is you."

"You've paid attention to my habits? Nanao-chan is so observant. I'm lucky to have someone so lovely watching me so closely." His eyes narrowed in what she presumed was mirth; the captain was quite enamored of his own wit.

"I am not—" she cut herself off. That was the reaction he wanted—firm denial that she'd ever been watching him, specifically, at all. But of course there was no way she hadn't been. One did not become a successful vice-captain without understanding one's captain's habits and tendencies.

"Enough to know when you're skirting around a point, yes," she said instead.

His eyebrows lifted towards his hairline—for once, he seemed not to have expected what she'd done. "Yare, yare," he said with a weary sigh. "You're merciless, Nanao-chan."

She narrowed her eyes behind her glasses.

He sighed again, reaching up with his free hand to angle his hat back a little. "We've received our assignments."

Nanao knew immediately what he meant. She swallowed. "When do we deploy?" she asked him.

"I'll be heading to the living world in… maybe a day, give or take."

It was impossible to miss what he'd omitted. "You?" Nanao's fingers tightened over her brush. "I've been led to understand that the fukutaichō would be deploying along with the taichō, when the time comes."

"Most of them will be," he said. His tone was sober—ponderous, almost.

Her jaw tightened. "And me?"

His shoulders drooped slightly. "Yama-jii needed someone to remain here, to handle the command of the Seireitei in the absence of the captains and vice-captains. That's you, Nanao-chan."

He wasn't looking directly at her anymore. Nanao bristled.

"He didn't choose me. _You_ did. You wanted to keep me away from the battlefield." The knowledge stung. Nanao knew—had always known—that she was more of an administrator than a warrior. She didn't even have a zanpakutō to call her own. But for her captain to confirm it in this way… for him to believe in her so little…

Her jaw tightened.

Kyōraku-taichō's expression was as open as she'd ever seen it. His smile had a melancholy edge; his eyes were soft and dark beneath the the weight of his brow. "Yes," he said quietly. "I did."

"I see." Nanao chilled her tone as far as she could—he leaned back slightly, as if struck. "Well, I suppose there's nothing to worry about, then. We both know how competently I can handle mere administrative matters."

She turned from him, returning her attention to her paperwork.

"Nanao-chan."

She didn't reply.

He didn't try again.

* * *

Uryū's breath rasped in his lungs. At his back, he could hear Karin's as well.

It hadn't taken long for their three opponents—the Privaron Espada, as they were called—to release their blades. Dordoni's had wind powers of some sort; Cirucci's feather-like blades vibrated at high frequency and moved very quickly. Gantenbainne's had the ability to fire orange energy projectiles. All of them were also capable of _cero_ ; in an enclosed space like this, that was highly dangerous.

But.

Uryū thought he'd figured out the best way to make use of his own abilities and Karin's, now. It was a delicate balance: one of their only advantages here was that their powers were in large part new and therefore undocumented. Uryū knew how powerful information could be, and without understanding exactly what method the Arrancar used to collect it, he was reluctant to give too much away too soon.

Still, stacked against the need to win the fight, he accepted that some concessions were necessary.

"Karin," he said lowly, "can you keep Gantenbainne and Cirucci busy for a few seconds?"

"You got it," she replied.

Flashing forward, she flew at Cirucci first. A bright arc of fire whipped from her blade, crashing into one of the razors attached to the Privaron's wings. The vibration dispersed most of the blow, but it was an effective distraction. Gantenbainne, being obviously the most honorable of the opponents, moved to assist.

Dordoni, being perhaps the _least_ honorable, seized the opportunity to attack Karin from behind.

Uryū, cloaked in Yorugen's concealment technique, waited for the exact moment he committed to the strike; in the meantime he reached back behind him and drew one of the Seele Schneiders at his waist. Deftly, he hooked the end of Yorugen's left-hand sword over his belt; it clinked softly against the reishi armor on the same side.

Dordoni lunged, air forming in a torrent at his fist. Uryū reacted, throwing off his Kagegaitō technique and cutting right through the wind with the Schneider. The reaitsu holding the attack together gave easily under the blade—the attack burst apart, gusting harmlessly in all directions.

Capitalizing on the element of surprise, Uryū used Dordoni's stagger backwards to close the remaining distance. Yorugen's right hand blade sought and found the Arrancar's _saketsu_. Uryū drove the Schneider into his _hakusui_ at the same time.

With a soft choking sound, Dordoni slumped forward. "Well done, niño," he muttered.

Grimacing, Uryū let go of Yorugen but removed the Seele Schneider, forming a spirit bow in his free right hand. Turning, he fitted the Quincy weapon to the string and drew back, aiming directly for Cirucci's wings. The arrow passed neatly over Karin's shoulder; the vibrations in it sliced right through Cirucci's defenses.

Calling Yorugen back to his hand, Uryū unhooked the second blade from his belt. Karin used the opportunity he'd given her to dig in and engage Gantenbainne directly; the crackling hum of Hisaku's fire was the loudest sound in the room now that Dordoni's wind was gone.

He had little time to focus on it, however—Cirucci had shed her feather-blades. They clattered heavily to the ground. "Ugh, those are such a suck on my reiatsu," she complained, flexing the thin remnants of her wings.

Uryū's eyes widened. "They're detachable?" He hadn't been able to tell, based on the way she was moving them before.

"Of course not," she replied. "I just got rid of them—they're dead weight."

"Got rid of—" he didn't have time to finish the question; the appendages that had been her wing-bones fused together behind her, extending into a long, whiplike tail with something resembling a fin at the end. Uryū flashed away from it, pushing off a platform of reishi in midair and launching himself in for close range.

His direct trajectory made him an easy target… but the fact that he's swapped places with his shadow via _Kage-e_ meant that her opportunity to hit him passed before she managed to. Instead of striking him square in the chest, her tail passed harmlessly through him. As he went by in the air, Uryū stretched his shadow long, passing it over her _saketsu._

He switched back in enough time to land; behind him, Cirucci collapsed.

To his right, Karin landed a heavy kick on Gantenbainne's jaw. He dropped as well, covered in burns and with a broken arm. None of them were dead—but two of them would never be using their abilities again.

For a moment, Karin stood over Gantenbainne, sword still aflame. But before he could wonder if she intended to kill him, the fire guttered out, and she turned around to face him.

"C'mon. Let's get out of here."

* * *

"Can't you run any faster?"

Yuzu resisted the urge to sigh. "Not at the moment, Grimmjow-san." Perhaps if she weren't completely exhausted, or had been able to exercise at all in the past month—but definitely not in her current condition.

He made a discontented grumbling sound, then drew to a stop. Confused, Yuzu did the same.

Grimmjow turned around so that his back was to her, then crouched. "Come on, I don't have all day here." He made an impatient gesture with one hand.

Yuzu blinked. Well, she supposed it was probably better to just comply, though it was a little… irregular. Still, she didn't complain—it was better than being summarily slung over his shoulder or carried underneath an arm or something. Gingerly, she looped her arms around his neck from behind, careful not to squeeze or anything. He gripped her knees with his hands, taking off with a hard jump.

It was smooth travel after that, though—his _sonído_ really was remarkably quick. His grip on her was firm, but not too tight; Yuzu shifted slightly. Allowing herself to relax eliminated any leftover bumping.

"There's another one with Zaraki," he said; the words carried over his shoulder to her, buffeted by the wind of their passage. "Is that gonna be a problem?"

It took her a second to decide that he was asking if the second person would interfere with a one-on-one match. Yuzu shook her head before remembering he couldn't see it. "I don't think so. Yachiru-san is Zaraki-taichō's vice-captain. If he intends an individual match, she won't interfere." Yuzu paused a moment, swallowing thickly. This was where things could get a little dicey.

"Um… Grimmjow-san?"

"What?" He pushed off a low roof, launching them both into the air again.

"You don't… you aren't going to kill Zaraki-taichō, are you?"

She heard him snort. "Ain't that the kind of thing you're supposed to deal with?"

It wasn't a guarantee, but… Yuzu breathed a sigh of relief. She was pretty sure that was Grimmjow-speak for 'I want to _fight_ him, not kill him.' Maybe it was thin difference, if they'd both be going all-out—accidental death was a very real possibility. But… if he was bringing her along and said it like that…

Maybe this would work out okay after all.

When they landed in front of Zaraki and Yachiru, the captain looked like he'd been expecting them. He spared her a glance and a small nod before a grin broke out over his face.

"Grimmjow. We finally gonna settle this, or what?"

The Espada wore a jagged smile to match. "You got that right. But first—Yuzu."

She nodded. Zaraki-taichō had a few minor injuries; nothing to suggest that he'd done battle with any of the other Espada yet.

He saw her looking at them and shrugged. "Some assholes tried to block our way up. Exe-somethin'."

Yachiru nodded. "But me and Ken-chan fixed that, didn't we, Ken-chan?"

Zaraki stood surprisingly still as she worked—Yuzu hadn't ever healed him personally before. She'd sort of expected him to rebuff her. But either he wasn't like his division when it came to healing or he was just as interested in an 'even' match as Grimmjow was; either way, he allowed her to apply the kaidō without a fuss.

Yuzu felt a subtle dread plucking at her chest, but it was obvious from one look at them that there was no stopping this—they'd both been anticipating it for a long time. The best she could to was be here to deal with the aftermath.

She hoped they didn't die.

Either of them.

* * *

"Well, well. Long time, no see, Sōtaichō."

Kisuke stood in front of the large screen set up in his room, leaning on Benihime with one hand. His other rested atop the hat on his head—a new one, now, without the chunk missing. He'd shaved a couple of days ago, which of course meant he was back to the usual level of stubble and whisker now. He might as well never have left, for the way he was handling the situation.

Yoruichi, standing behind him and leaning on the doorframe, thought he might have actually shown some concern when she'd told him about Uryū and the Kurosakis, but it was gone quickly. As far as she could tell, everything else she'd done in his absence was entirely according to plan. She'd resigned herself to being utterly transparent to him a long time ago; fortunately, he was just as easy for her to read. Most of the time.

Right now, he was actually enjoying the fact that the Sōtaichō needed his help. But not too much—because there would always be a part of him that hesitated, just a _tiny_ bit, in front of people with status. So he smiled, but didn't dare let it become genuine.

"Kisuke Urahara," Yamamoto replied, his voice weighed down. He'd always had a sense of ponderous gravity about him—it was to be expected, from someone in his position. But Yoruichi detected an edge of weariness to it that was not there before. Too many nights with too little sleep, perhaps.

When followers suffered under the strain of something like this, leaders suffered double. That was just what it meant to lead.

"Something I can do for you?" Kisuke, by contrast, kept his tone light; almost playful. As though he led nothing at all, when the exact opposite was true.

"I am sending reinforcements into Hueco Mundo to assist the advance party. In anticipation of Sōsuke Aizen focusing his attention on the Jūreichi, I have ordered the Twelfth Division to construct an exact replica on the outskirts of the Rukongai. The two need to be switched; we lack the technology to do it." The Sōtaichō's words were steady. It couldn't have been easy to admit it though—to admit that a crucial part of his plan required the assistance of someone whose obedience he could not simply count on.

"I see." Kisuke tapped Benihime on the tatami floor a couple of times, his fingers curling over the handle. They had yet to re-acquire the ink stains Yoruichi was so used to seeing there, but the calluses were heavier than she remembered them being.

Just what had he been doing for nearly half a year?

"Will you do it?"

Not _can_ you. Will you. It seemed the Sōtaichō remembered just as well as anyone who to go to when you needed something done that looked impossible. Yoruichi felt an involuntary stab of pride in her best friend. She might still be mad at him, but this—the late-stage save—was exactly what Kisuke did best.

He hummed. "Not for free," he said slyly.

Yamamoto visibly bristled. But he knew as well as Yoruichi did that he had no choice. "And what do you demand in return?"

"I think we can all agree that Central 46 was in error when they ordered the disposal of the Visored. And when they sentenced Tessai to prison and Yoruichi to exile. I'd like to not be wanted dead, too, come to think of it." Kisuke tipped his head to the side, the artificial smile widening. "I think making all that go away would be a good idea, don't you?"

"I cannot simply—"

"Actually, Sōtaichō, you can." Yoruichi uncrossed her arms and stepped forward. "We all know Central 46 has ceded authority to you for the extent of the war. This version has barely been in place for five years anyway—they can't countermand you if you pardon someone. Right now, the authority is yours."

Yoruichi knew that Yamamoto's instinct was to achieve his aims while changing as little as possible. She even understood _why_ he thought that way. But that didn't mean she'd put up with it. Not for something like this—Kisuke had maneuvered them into a position where they could make demands. She knew he'd have no issue with her making a few of her own.

A glance sideways confirmed it. He bobbed his head, the curve of his mouth subtle now, rather than overt. He appreciated her brand of savvy just as much as she appreciated his.

They were never better than when they worked together.

"You can _also_ agree that neither Kurosaki sibling, nor Ishida, will face any form of punishment for the actions they have taken on behalf of the Gotei 13 or each other. Nor that any member of the advance team will be tried or punished for insubordination because they went on a perfectly reasonable rescue mission."

Yamamoto pushed a heavy breath out his nose. "Is that all?"

They exchanged a glance. Kisuke shrugged.

"Sounds good to me. I can have your replica swapped with the real Karakura town in… eight hours."

Yamamoto considered that, then nodded. "Very well. I agree to your terms. But only if you succeed."

Yoruichi matched the nod with her own. That was fair enough, she supposed. The screen flickered and went dark.

"I forgot how fun it is to watch you work, Yoruichi," Kisuke said offhandedly, already shuffling things around on his shelves, pulling down various books and devices. "I was half-expecting you to demand a pension plan, next. Or back pay for the last hundred years."

Almost despite herself, she smiled. "You can only push the Sōtaichō so far, Kisuke. I just asked him to do things he at least sort of wanted to do anyway. If I'd tried to get back pay, he probably would have risked having the Twelfth try and work out a way to switch the towns."

His eyes narrowed with the force of his grin; the glint in them was more familiar to her than her own hands.

Maybe she was still a little mad at him for disappearing on her like that. She'd yell at him later. Right now, they had work to do.

And however dangerous it was, she knew she was going to enjoy it. "We're never going to die peacefully, are we?"

"Never," he confirmed.

* * *

 _Term Dictionary_ :

 _Guncho Tsurara_ – 群鳥氷柱 – "Icicle Flock." One of Hyōrinmaru's bankai techniques. Launches a volley of icicles, basically.


	14. Chapter Fourteen:Bound to Take Your Life

_Content Warning:_ Gaslighting. And some body-horror-type stuff, if that bothers you. But it's all canon-typical.

 _Note_ : Some parts of this chapter call back to _Covalence_. Rukia's thought process might not make a lot of sense of you haven't read the second chapter of that fic.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Fourteen: Bound to Take Your Life

* * *

"Are you really… Kaien-sama?"

Rukia wasn't sure she could believe it. His face was exactly as she remembered it, but…

That wasn't the only thing she remembered. She definitively recalled the moment he'd gone slack in her arms. The moment he'd stopped breathing, and his body had disintegrated into reishi particles. Just like all souls did when they died.

He smiled. "It's been a while. You're looking well, Kuchiki." With a casual hop, he descended from the upper level he'd been standing on, landing on the ground ten feet away from her and mumbling something about his clothes being a pain.

That was what really confused her—he didn't just _look_ like Kaien. He acted exactly the same, too. It was enough to make her hesitate. She wanted to believe what she was seeing, but… her eyes had deceived her before.

He glanced up, his eyebrows approaching his hairline. "What? What's with that look? I'm alive, Kuchiki! Aren't you even a little bit happy to see me?"

Rukia's lips parted to say something—she didn't know what—but the words simply wouldn't come. If this… if he was simply a facsimile of the real Kaien… he was indistinguishable. Could it… could it really be…?

He stood there, frozen in an expression of incredulity and good humor that was so perfectly like him it could have been ripped straight from her memory. "Kaien-sama, I…"

The expression softened—he sighed and half-shook his head. "It looks like you do believe me." He sounded so relieved. Had he doubted?

Should _she_?

The brightness of the smile blooming over his face said no. With a gesture, he invited her to sit, flopping down himself with no reservations. He folded his legs crossways underneath him, leaning forward so his elbows were on his knees. Gingerly, Rukia followed suit—though she sat seiza instead, hands curled into fists on her thighs.

"I guess I owe you an explanation," he said, tilting his head slightly to take in her obvious discomfort.

Not trusting herself to speak, Rukia only nodded.

"That night… my body had begun to collapse right after the battle. And after I said goodbye to you, it crumbled away into pieces… like they usually do." His brows knit for half a second—perhaps he was thinking of Miyako.

She swallowed.

"In that state, it flew to Hueco Mundo. That Hollow—Metastacia—was one of Aizen's experiments. When destroyed, it came here to reconstitute itself. I dunno why it had that kind of mechanism, but… when it did, it took on my form. Probably because it had absorbed so much of me. I guess that must have been according to their plans, but… for some reason, my will was in control of that body."

Rukia considered that. The phenomenon wasn't entirely unheard of—well, the reconstitution was, but not one particular will taking over a Hollow. It was how Gillians became Adjuchas. That much was well-documented. And… she definitely couldn't put it past Aizen to create a reconstituting Hollow.

"Anyway," he said. "I was able to take back my body, and I secretly took the place of one of the Espada. I've been waiting for a chance to strike back at Aizen."

"But—" Rukia bit her tongue. "But why not warn Soul Society?"

If he were alive this whole time… if he'd known about Aizen and the Espada this _whole time_ …

He could have stopped everything. And he would have, if he were Kaien-sama.

The corners of his mouth turned down. "I couldn't," he replied. "I can't open gargantas on my own. I had no way of getting a message to anyone. Believe me, Kuchiki—I wanted to. But you know what Aizen's like: the first sign of anything strange in my behavior, and I'd have lost any advantage I had."

Her reservations must have shown on her face, because he continued.

"Outside… there's a blue sky, right?"

Rukia nodded.

"Aizen created that sky inside of Las Noches' dome; all the places that its light shines down are under his surveillance."

"Wha—" Rukia figured that explained his insistence on darkness, but was such a thing even possible? It had to be.

"I'm glad you were the one that came here," he said softly, lowering his head to stare at his hands. "You may be the only one I trust to carry out the strategy I have."

Rukia's fingers tightened against her palms.

"Let's change locations." He stood, lifting his eyes to meet hers. The resolve in them was so familiar. Like nothing had changed at all. "Come on, Kuchiki."

Rukia was on her feet almost automatically. "Yes, Kaien-sama." It was him. It had to be him. No one else could—

It was by virtue of sheer instinct that she leaned backwards in the nick of time. Even though she did, she felt the blade of his sword drag along the skin of her face, just beneath her eye. If she hadn't dodged right then…

"What's this?" He blinked slowly down at the tip of his zanpakutō. Blood—her blood—dripped from the edge to the floor, glimmering darkly. "It seems like you've gotten better." He smiled, flicking the rest off the sword with an easy motion. "If that was the old you, you would have died from that thrust just now."

"Wh—what… how much of what you just said was true?" Rukia focused on her breathing. She'd just begun to believe—

She shook her head, trying to dislodge the thought—and the fresh wave of grief.

"How much?" he echoed. His eyes narrowed. "All. Of. It." His enunciation was slow, deliberate. One brow lifted; he regarded her quizzically. "Is there something strange about my trying to kill you? You haven't forgotten, have you?" With his free hand, he jabbed a thumb at his own chest.

"I am Kaien Shiba, former fukutaichō of the Thirteenth Division." His eyes fell to the badge on her arm; he dropped his wrist forward so that he was pointing at her. "And you… you're Rukia Kuchiki, the woman who killed me with her own hands."

Blood on her hands, on her zanpakutō. The weight of another person, supported by her feeble strength. The loss of warmth as she felt him die. The sudden shudder of his body breaking apart.

The feeling of closing her hand over empty air, trying to keep some tiny piece of him with her.

She remembered.

"Are you prepared, Kuchiki? To offer your life as atonement to the man you killed?"

His voice was a knife in the dark—it struck her suddenly, where she didn't expect. He'd attacked her, but… her life in repentance for what she'd done?

 _It sounds to me… like you did him a favor._

Rukia sucked in a breath. Her hands trembled, but…

 _And I am even more certain that someone like you describe Shiba-san to be would not ever have wanted to be the reason that his friends or subordinates came to harm._

Never wanted his subordinates to come to harm. Yes. That was true. Kaien-sama was exactly like that. Always looking out for other people. He would never.

He would _never._

"How _dare_ you!" Wear his face, use his name. Try and manipulate her into surrender with such dirty tricks. Make her doubt herself, her friendship with Kaien.

How dare he.

Rukia's hand, steady and unerring, found the tsuka of her zanpakutō. " _Mae, Sode no Shirayuki_!"

* * *

Renji had made three attempts to summon Sōō Zabimaru—each time, the blade had burst apart, leaving him holding only his sealed katana. It was like… something was unstable. It didn't make sense. He could get the bankai to form, but not to _stay_ formed.

"Still haven't figured it out?" Szayelaporro, flanked by his two-person fracción, casually flicked some hair out of his face. "Well, I suppose that's to be expected, for a simpleton such as yourself. Allow me to explain."

Not much for gabbing during a fight himself, Renji figured that if the guy was going to give the information up for free, he might as well listen. Maybe there would be something he could use.

"You can't use that bankai in this room. You see, all the information about it: its shape, its abilities, even the way it arrives to spiritual composition via your reiatsu… all of this data has been delivered to me in perfect condition. And so," he gestured to the room around him. "Utilizing that information, I created a mechanism to seal your bankai within these quarters."

But that was… "Something like that could only be understood by someone who's been hit by it." Renji would have remembered this asshole.

"Well… yes," Szayelaporro replied. " _Luckily_ for me, _you_ happen to be the shinigami who fought and killed my useless brother, Yylfordt."

Renji _did_ remember _that_ asshole.

"Shit."

"A rather accurate statement of your circumstances. I applaud your concision. It's a rare trait." With his right hand, he drew his zanpakutō from the same hip. "Now… as this is the first time I've had a body capable of bankai before my eyes, I would appreciate it if you could—to the best of your ability—stay calm… and die with all your limbs intact."

Renji sidestepped the initial lunge—he was probably faster than this guy. But without bankai, he didn't know how much difference that was going to make. He flung his shikai for Szayelaporro's side; the Espada batted it away with his sword. Renji jerked his arm, sending a ripple through the extended Zabimaru that became a lash. That time, he cut; a shallow gash appeared on the Arrancar's shoulder. It stained the white of his uniform deep red, but the bleeding halted before it got too far.

Clicking his tongue against his teeth, Szayelaporro frowned. "I see. Well, I suppose I don't need _all_ your organs."

Deftly flashing away from Renji's third attack, he reappeared behind him. "I'm really not much of a warrior, you know. I consider myself much more a scientist than that. But if you insist on fighting like this, I suppose I must subdue you quickly. _Susure, Fornicarás._ " With the release command, he lifted his zanpakutō, angling his head back.

Was he really—

Sure enough, Szayelaporro _swallowed_ the zanpakutō. His reiatsu changed; some of it became a mist or something. It was hard to see exactly what was going on; Renji would have attacked if he had any clue what the hell was going on in there. But he figured at this point it was probably better if he didn't risk it.

Instead, he used the opportunity to shoot a _shakkahō_ at the roof. Maybe if he could break the room apart, he'd regain the use of his bankai. He felt like he was gonna need it, if he wanted to live through this.

The fireball spell crashed into the ceiling. The riblike pattern in it cracked; pieces of the stone broke off and fell towards him. But he knew the room above had no support beams or anything in it—it was just an empty dome.

He'd just let off the second spell when he was engulfed from behind by… something. It felt like a fleshy membrane of some kind. It clung tight enough to seriously hinder his movement; the smell alone was enough that he nearly gagged. Punching it turned out to be completely useless; he was raising Zabimaru to try and cut his way out when it receded seemingly of its own volition.

Grimacing, Renji gulped in fresh air and spat to the side; if there'd been any time, he would have tried to shake off some of the filmy fluid he was still covered in. Apparently, the thing that had swallowed him was a part of Szayelaporro's released form—and he had three more. They were arranged like branches sticking out of his back. He kind of looked to Renji like some kind of weird sea plant or something.

He risked a glance at the ceiling. There was a hole in it; he could see bright white above. He had to try it. "Sōō Zabimaru!" The reiatsu collected along the blade like always; the problem was keeping it together.

"I already told you that isn't going to work!" Szayelaporro lashed with two of his other branch-tentacle… things.

Renji whipped his right arm forward, extending Zabimaru's blade from the snake skull. It sliced through the incoming limbs—and then it burst apart, as it had before.

Szayelaporro seemed surprised by it, though, drawing the stumps back with a hiss. "Well, well. It seems even with so much help, Yylfordt managed to miss the important details."

"I didn't use that part against him," Renji replied, swinging his shikai in a wide arc to force his opponent back. "It's still not that stable, so I guess it must be pretty hard to calculate exactly what it's gonna do."

"Hm," the Arrancar sneered. "How unreliable. I don't feel so bad about destroying your body, now."

Renji readied himself. One of the remaining branches moved to hover over Szayelaporro's hand. There was a gush of some kind of black liquid. When it fell to the floor, what remained in the Espada's grasp was… a doll? One that looked disturbingly like Renji himself.

"Let's say that this is you, shall we?" The Octava smiled slyly, tapping the doll's head with a finger.

Renji's free hand went to the back of his head. He could have sworn he'd just…

"Felt that, did you? How about this?" Szayelaporro relaxed his hand slightly, scissoring one of the doll's legs between his last two fingers. In a swift motion, he bent the leg at an unnatural angle.

Renji's right femur snapped. He felt the bone break skin and bit down hard on his tongue, adjusting his balance to stay on his left foot. He didn't know how that was happening, but he sure as hell didn't plan to stand around while it happened again. Shifting his weight, he pushed forward into _shunpō_.

* * *

When Yuzu had told him that doing that _Jinzen_ thing would help him in a fight, Grimmjow hadn't expected this much out of it.

It wasn't that any of his physical abilities were better—he was as fast and as strong as he'd been before. But something _else_ was different. The way his power used to claw around in his head like his skull was about to split open had stopped; or at least it had settled. He felt more… focused.

Since he was having just as much fun, though, he couldn't complain.

Zaraki swung his sword, splitting the air with a low whistle. Grimmjow twisted, feeling the aftershock as it passed by his head. He thrust his own zanpakutō in retaliation; it found Zaraki's shoulder. The other guy might as well have had hierro—his reiatsu was that much of a shield. But Grimmjow's was sharp; the wound wasn't as bloody or deep as it could have been, but it sure as hell cut.

"Heh." Zaraki glanced down at the new wound, the latest in a series for both of them. "You've gotten better. This is gonna be even more fun than I thought."

Flicking blood off his fingers, Grimmjow flashed a jagged grin. His nerves were sparking again, but now it felt a little more like they did it for a reason. Like everything in him was pointing him forward. Through this fight. It was gonna be damn fun… _and_ he was gonna win.

"We're just getting started," he replied.

Zaraki had shed the eyepatch from the get-go. Since he didn't have a bankai, Grimmjow figured it was about the same idea. He should probably return the favor.

" _Kishire, Pantera_."

The sonic wave from the release pushed Zaraki back half a step—Grimmjow pounced. His first strike raked against the shinigami's chest, opening four long welts in his skin, but the follow-up clanged off his sword. Good—he was adjusting quickly.

Grimmjow's ear twitched; he flashed away from Zaraki's next blow, laughing.

"Faster!" he snarled, the word rolling off his tongue with no anger. Just enthusiasm.

Zaraki went with it, weathering Grimmjow's assault like a tower in a storm. The speed and strength of their strikes increased, until hierro and reiatsu-protected skin alike were both useless _and_ necessary: useless to stop a strike, necessary to stop even the barest one from slicing either of them clean in two.

He couldn't rely on his ears anymore—by the time he heard the incoming swings of Zaraki's sword, they were already too close to get away from. Clashes of his claws on the metal blade, and the screeching scrape that went with, seemed to follow the actual contact by a delay of half a second. Grimmjow's muscles strained, pushed to their limit—Zaraki took in air like a fuckin' bellows, only faster. Both of them were quickly soaked in a familiar cocktail of salty sweat and metallic blood—Grimmjow's tongue curled in his mouth, rasping against the roof.

They built to a frantic rhythm—and then he broke it, stepping away with _sonído_ and firing a _gran rey cero_ point blank at Zaraki.

The smell of burnt flesh flooded his nose; when the dust cleared, the shinigami was missing most of his uniform—the right shoulder hung on by a ragged strip of fabric, but the white coat had been incinerated. Smoke rose from his shoulders—there was an angry red circle just under his ribcage.

Huh. Here Grimmjow had thought Ulquiorra was the only one who aimed instinctively for where his own Hollow hole was. He guessed maybe he did, too.

"That's a helluva blast you got there." Zaraki cracked his neck to either side.

But he wasn't fooling Grimmjow—both of them were feeling it, now. It'd come down to the next few exchanges. Who could hit harder, faster—and with better aim.

Shifting his stance, Zaraki bent his knees, taking hold of his zanpakutō with both hands. "Hope you got somethin' else up your sleeves, Grimmjow, or this last bit's gonna be pretty boring for me."

As it so happened… he did.

* * *

Even the way he _fought_ was the same.

Rukia pulled in air, flinching when her broken rib protested. Well—he fought the same, except without holding back. The multitude of small cuts and several bigger gashes she was sporting could attest to that.

Sense memory was a strange thing—no matter how much her intellect insisted that this was _not_ Kaien-sama, her instinct screamed that it was. Everything was exactly as she remembered it, from his fighting stance to the way he barked instructions at her during their exchanges. He even knew her first two shikai techniques.

He would; the real Kaien-sama had helped her develop them.

She knew that if she continued to rely on that memory, the understanding she'd had then, she would never escape this. If she let her instinct take over, she'd slip back into the same patterns he knew—his presence alone would lull her into it. She'd become again the person she'd once been.

But she _wasn't_ that person anymore. Leaping clear of a surge of water, Rukia flashed behind him. Instinct had her swinging Sode no Shirayuki for his free arm. Insight drew her blow short, before he could catch the blade on the prongs of the trident as he had so many times before. The result was that she wasted her opportunity; Rukia stepped away before he could catch her in a counterattack.

She was stronger than she'd been then; it was time she started acting like it.

It wasn't what she knew of him _then_ that would make the difference. It was what she knew of this imposter _now._ And one thing she knew was that he wanted to stay out of the light.

" _Hado #33: Sōkatsui!_ "

The Arrancar bent himself easily away from the spell, but Rukia hadn't been aiming for him anyway. Behind him, the blue fire slammed into the wall, breaking it open. Sunlight poured in through the break; as she'd suspected, the imposter moved quickly to be away from it. That would be it, then: her strategy.

Charging up the spell again, Rukia shot it at a different angle, punching another hole in the structure. Another shaft of light speared through the dark chamber. On the third attempt, he figured out exactly what she was doing and jumped for her, swinging Nejibana around and throwing a torrent of water at the spot where she was standing.

Drawing her zanpakutō around her in an arc, Rukia activated _Tsukishiro_ —the water flash-froze inches from her face. Her breath left her in a little cloud, sinking towards the floor. Pulling in another, she moved clear of the spot with _shunpō_ , still focused on putting holes in the walls and ceiling. It was some kind of weakness for him—exactly what would change, she'd just have to see.

Ten spells later, she finally got him. Sunlight fell over his face, illuminating Kaien-sama's features for just a moment before they burst apart. Rukia gasped—even knowing he was an imposter, knowing for _certain_ , hadn't prepared her to see that. The way the skin and cartilage and hair peeled away, dissolving into nothing. She shuddered.

What remained was… a glass tank? Two small heads were suspended inside of some fluid atop the Arrancar's body. It was… Rukia would say nightmarish, except that not even her nightmares were so outright bizarre.

If she survived this, that might change.

"Tch. So it came off." The Arrancar raised… their?... hand to the tank. "Well, I guess it's no use. Allow us to reintroduce ourself then. We are the Novena Espada: Aaroniero Arruruerie!" The heads leered from inside their tank; she could hear them with full clarity despite the glass and liquid in the way.

It felt like some last shred of binding on her limbs broke; her instincts realigned with her conscious thoughts, and all of her was equally disgusted. Pursing her lips, Rukia brandished Sode no Shirayuki. "And I'm Rukia Kuchiki, fukutaichō of the Thirteenth Division. On behalf of my mentor, Kaien Shiba-sama, as well as everyone who knew and looked up to him… I'm going to kill you."

She raised her free hand to begin a kidō incantation when they brought her up short.

"Can you?" Aaroniero stepped back into a shadow. As if the previous few moments had just been rewound, Kaien's face reappeared over the tank; he smiled wryly at her. "Not everything was a lie, you know. My power allows me to consume other Hollows and evolve. I devoured Metastacia, and when I did, I gained everything that was left of Kaien Shiba. His memories, his powers, even his zanpakutō—all of these are a part of me now. Do you understand what that means?"

Rukia's heart stuttered; for just a moment, her grip on Sode no Shirayuki wavered.

 _I'd do it again if I had to._

 _It's the same, isn't it? Necessary, but still painful._

She'd never imagined actually _needing_ to do this again, but… Ishida had been correct. She'd done the right thing, back then. And it was still the right thing now.

" _Bakudō #4: Hainawa_!" She hurled the yellow kidō rope from her hand with a sharp flick; it wound around the Espada's body.

"You think you can hold me with such a weak spell as this?"

Rukia shifted her hand until she was pointing at him with her index finger. " _Bakudō #61: Rikujōkōrō._ "

It was an interesting coincidence, that the six rods of light produced by the weaker spell could be used for the stronger one. They shifted in place, stabbing through Aaroniero's core from three different angles. Her brother had taught her that.

And her captain had taught her something useful, too. " _Carriage of thunder, bridge of a spinning wheel,_ " she chanted, pushing more reiatsu into the active spell to strengthen it. " _With light, divide this into six!_ "

The Espada's movement halted altogether—the spell reinforced with the chant held him fast. She knew it was only a matter of seconds, though. He had more reiatsu than she did; that he would break free eventually was a foregone conclusion.

So Rukia did something she'd learned all by herself.

Raising Sode no Shirayuki to the level of her shoulder, she focused her reiatsu on the end of the blade, lowering her body temperature by another ten degrees. " _San no mai: Shirafune._ "

Ice burst from the end of the blade, lancing forward. Her reach exceeded Nejibana's by at least a foot—and the sharp edge of the technique pierced the spot between Kaien's eyes. The disguise faded again; the tank burst apart, spilling both Hollow heads out onto the ground. The body collapsed; nothing more than an empty husk soon to dissolve. Shrieking curses at her and calling for Aizen to save them, the Novena Espada died.

Drained, she sank to her knees. Sode no Shirayuki reverted to her sealed state; Rukia braced her palms on the ground. Carefully, she raised her body temperature again, closing her eyes to focus as well as she could on the process. She still needed practice, but… all the extra training she'd done had helped.

Rukia moved her free hand to her ribcage, groaning softly at the injury there. She'd expected to feel… guiltier. She'd just erased everything that was left of Kaien-sama from this world, after all. But…

"I'd do it again if I had to," she murmured.

As many times as it took. Because nothing that was left could be him anymore. And she… she wasn't who she'd been anymore, either.

That was okay, now.

* * *

Hanatarō swallowed past the lump in his throat, edging slightly closer to his captain. She could be a pretty scary lady, but at least he knew her. By comparison, Kuchiki-taichō and both of the Kurotsuchis were downright terrifying. Yuzu-chan's dad didn't seem so bad, but he had a serious look on his face, and Hanatarō didn't want to be rude and interrupt him if he was thinking about something.

He couldn't imagine having to go into Hueco Mundo to rescue his own child. Knowing that he had friends whose lives were at stake was bad enough; he really hoped that Yuzu-chan and the others were all right.

But that was why he'd volunteered to come—Kotetsu-fukutaichō couldn't go since the captain already was; so it had to be one of the other officers. Iemura-san might have been a better choice, but he was still recovering from a month of being the only healer the advance team had. No one else had looked all that eager to go—but Hanatarō wanted to.

So here he was, about to get his first look at Hueco Mundo, the realm of the Hollows. Clenching his fists in his hakama, he pulled in a shaky breath and braced himself. The garganta opened—a line in the air in front of them at first, it gradually yawned open like a mouth. All of them stepped through together.

"Remain close, Yamada-san." Unohana-taichō's instructions were mild; though she never really stopped being that way, it was still somehow easy to tell when he was in trouble with her and when he wasn't.

Fortunately, right now he wasn't. As he'd been told to do, Hanatarō guided his reiatsu out in front of him, forming a smooth path he could follow beside the others'. Of course, he was here with three captains, a vice-captain, and a _former_ captain, so he had to work hard just to keep up. But he did—that was something.

Eventually, he spotted a light up ahead. That seemed like what they were looking for; everyone shifted slightly to angle themselves towards it. When they passed the boundary, they were deposited in what looked like a city—except all the buildings were completely white and most of them were domed. Despite the sheer number of them, he felt a sense of… emptiness, about it.

The weirdest thing had to be the reiatsu, though—he couldn't feel any. Even Unohana-taichō's disappeared from right next to him, despite the fact that she was standing _right there_. Something must be blocking his ability to sense it.

His captain frowned slightly, narrowing her eyes. From the way she tilted her head ever-so-slightly to one side, he guessed that she must be able to sense something that he could not.

"Yamada-san," she said, glancing at him from the corner of an eye. "Please accompany Kuchiki-taichō. I believe Kuchiki-fukutaichō is injured, but she is nearby."

Unohana exchanged a glance with Kuchiki, who nodded. Hanatarō wanted to ask what the others were going to do, or where they should go afterwards, but he didn't get the chance—Kuchiki was already moving away. Considering how well-known he was for the speed of his _shunpō_ , Hanatarō was immediately afraid he'd be left behind. Bounding into his own flash steps, he tried to keep the ends of the captain's scarf in sight—not easy when everything else was the same color.

But as it turned out, she really _was_ close. Kuchiki stopped before he completely left Hanatarō behind, in front of a building with lots of holes in the ceiling. Pushing open the door, he led the way inside. Hanatarō followed.

The room was cold; that was the first thing he noticed. It was also dark, but the breaks in the ceiling punctuated it with beams of light. Laying half-in, half-out of one of them was Rukia-san. Sucking in a breath, Hanatarō jumped off the staircase and hurried to her side, shrugging his medical equipment off his shoulder and into the crook of his elbow.

"Nii-sama… Hanatarō-san." She was awake, at least.

Hanatarō lit his hands with diagnostic kaidō, passing them over her limbs first, and then her abdomen. She'd broken one rib, cracked another, and had several lacerations, but probably the worst thing was just that her reiatsu was very depleted.

"Nothing life-threatening," he said, more to himself than either of them. Glancing up at her face, he offered a thin smile. "Don't worry, Rukia-san. I can fix this."

It might take a while, but he could do it.

* * *

 _Term Dictionary_ :

 _Fornicarás_ – 邪淫妃 – The kanji are "Lewd Concubine," whereas the Spanish means "You Fornicate," I think in the sense of a command. Honestly, Szayelaporro's ability set is freakin' squicky (and that's _before_ even touching the whole "Gabriel" thing). Anyway, the release command is _susure_ (啜れ), the imperative of "to sip."

 _Pantera_ – 豹王 – The kanji are for "Panther King," while the Spanish is simply "Panther." Grimmjow's resurreción, of course. The release command is _kishire_ (軋れ), or "grind." The sense of this 'grind' is the thing you do with your teeth.

 _Nejibana_ – 捩花 – "Spiranthes." Spiranthes is a genus of orchids. Derived from the Greek for "Spiral Flower." The kanji can also be read as something like "Twisted Flower." Kaien Shiba's zanpakutō, and also what Aaroniero uses to fight. I kinda bypassed _Glotoneria_ for a couple reasons, the biggest one being that the ability to devour Hollows isn't that helpful in a fight against a shinigami you're trying to gaslight by pretending to be her dead mentor. Nejibana's ability is to generate and control water.

* * *

So I like… just read the last manga chapter today. Sigh. I gotta say, writing this AU has been very helpful in terms of helping me not wig out at all the unanswered questions left in canon. I won't spoil anything, but I hear the fandom fallout has been pretty nuts.


	15. Chapter Fifteen: Bad Moon (Reprise)

_Content Warning:_ Major character death, you guys. Also creepers being creepy.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory AU_

Chapter Fifteen: Bad Moon (Reprise)

* * *

"You're a stubborn fellow." Szayelaporro said it with an air of bored weariness. "I've crushed so many different things… I'd say it's about time for you to lose consciousness already…"

Renji felt like he was just about there—he'd lost track of exactly how many of his internal organs were squashed, but from the burning in his guts, his stomach was included. Blood rose up in his throat, nearly gagging him before he spit it out. More of it spilled over his lips and jaw, warm and sticky.

His lungs must have still been working, though—he felt more blood bubbling when he pulled in air.

Zabimaru scraped along the stone floor as Renji tried to bring him back around to his front. Bracing his hands on the ground, he struggled to stand, lifting his head to watch his foe. Szayelaporro looked down his nose at him—but he wasn't unbloodied either. Another one of his branches had been cut off at the middle, and there was a new gash crossing his chest from shoulder to hip. Renji had paid heavily for every wound he'd inflicted; too heavily.

He'd just gotten his feet under him when the Espada sighed. "You're so tiresome."

A loud _snap_ echoed in the room; Renji felt his left arm sag underneath him, now completely useless. Unable to compensate in time, he crashed facefirst back onto the ground.

"I've decided that from here on out, I'm going to sever the tendons in your body one by one." Szayelaporro said it blandly, like the decision was totally everyday and boring. "Your internal organs are more closely related to your life, after all. So at least behave yourself while I do, hm?"

Renji turned his head to the side, but from the angle he was at, it was impossible to see what happened next. He felt a tendon in his right arm break just like the one in his left, but then the reiatsu in the area flickered—something vaguely familiar was here.

"Well, well…this is quite the interesting scene."

It took him a second to place the voice. But there were only so many people in the world who could sound that smug and bored at the same time. Kurotsuchi…?

"Oh? And who might you be?" Szayelaporro had basically the same tone—but with more boredom and slightly less smugness.

"'Who might I be?'" Kurotsuchi echoed. "Is there any point in answering such a question?"

Next to him, Renji felt another presence. Carefully, a hand fit under his shoulder and turned him over onto his back. His vision was blurry, but he could make out dark hair and a pale face.

"Please remain still, Abarai-fukutaichō. Further movement in your condition may result in death."

Yeah—that was the other Kurotsuchi then. She definitely lacked Isane's bedside manner. Renji kept still; it wasn't like he had any other choice. He could hear the rustle of fabric—the Twelfth had at least some healing capability, but it wasn't generally as painless as what the Fourth did. He kept his focus on the confrontation between Kurotsuchi and Szayelaporro—it was upside-down, but he could at least track their movements.

* * *

Rangiku panted heavily—trying to keep this guy away from the captain was a real pain. Her lungs felt raw, like someone had scraped over them with sandpaper. Zommari was quick, but she was keeping him at bay—barely—with Haineko's ash and kidō.

On the ground not too far away, Tōshirō was moving around a little. She thought that meant he was conscious again; if it'd taken him any longer, she might not have lived to see it.

"Captain! A little help?"

He rolled over, putting his hands underneath him and climbing back to his feet. Hyōrinmaru was busted up in a bunch of places, but with Tōshirō awake again, the ice started to repair itself. Zommari stepped back into that Arrancar- _shunpō_ thing; Rangiku tried to keep track of which one was the real one, but they were totally identical as far as any of her senses could tell her.

Just great.

She tried to flash away, but Zommari caught her by the ankle and swung; Rangiku slammed back into the wall behind her. She felt it crack—splinters of stone dug into her back and her vision whited out for a second.

"Matsumoto!"

A sheet of ice appeared in front of her face; Zommari's next kick shattered it. But it was just enough time for Rangiku to take back control of her body and get out of there. She nearly ran smack into another Zommari—just how many times was this guy going to use his stupid cloning technique?!

" _Getsuga Tenshō_!"

A bright wave of reiatsu blew past Rangiku, tearing at her hair and shihakushō. Her face on the same side felt hot—she was sure the skin was red. But the attack hit exactly where it'd been aimed—the Zommari beside her disintegrated into nothing.

The technique was as familiar as any of her own. Coughing, she waved away the smoke and debris floating in front of her face. When it cleared, she could see Isshin—he gripped Engetsu loosely in one hand. He'd released it; the blade was covered in hissing, popping blue-white fire. His other hand rested casually between the layers of his uniform; she noticed his old haori was something like a scarf, now, bunched up on one side and laying over his shoulder.

"How's that for an entrance, huh?" He grinned, flashing teeth.

"You idiot! We're underground! You could have brought the whole building down on us!" Tōshirō glared; suddenly he wasn't showing his injuries nearly as much as a few minutes ago.

Scratching lazily at his chest, Isshin shrugged. "Nah. I knew it'd be fine. Now—what are we dealing with here, you two?"

Just like that, everyone's focus was back on the battle in front of them. Rangiku frowned.

"One of those Espada guys. He can make clones of himself with that _shunpō_ thing they do."

"You don't say—"

" _Shizumare, Brujería._ "

"—and there goes his release," Rangiku finished. Swallowing, she tasted that nasty metallic flavor—blood and bile.

The new Zommari actually looked a lot less like someone who'd be moving around all over the place and fooling them with speed. He'd kind of… puffed up, until it looked like he was sitting on a fat mushroom cap or something. Except it was covered in eyes, and… weird.

"Well. Guess we'd better hurry and wrap this up then," Isshin said, leveling Engetsu out at the Arrancar.

"Such arrogance, to presume that it will be so easy," Zommari replied.

The pain in her ribcage made Rangiku pretty sure that there wasn't really any arrogance happening here. _She_ sure knew it might be hard. They'd do it anyway, though.

One of the eyes on Zommari's bottom half opened; it looked right at Isshin and dilated too quickly for a normal eye. Rangiku braced herself for an energy attack or… something—but nothing seemed to happen.

"Huh." Isshin looked down at his left arm.

Rangiku followed his eyes—there was some weird kind of black mark on his hand. It looked like a tattoo, in the shape of a sun, maybe.

"I see that you do not understand. This is my power—Brujería steals the sovereignty of whatever it looks at. In this case… your arm is now mine to direct as I wish."

Before any of them could react to that news, Isshin's left arm lashed outwards. Rangiku gasped, only for the sound to cut off suddenly—his fingers closed over her throat and lifted her into the air. Not _this_ again! How many people were going to choke her before the war was over?

More importantly, what was she supposed to do _now_? She couldn't just cut him!

Rangiku met Isshin's eyes; she was surprised by the flash of panic she saw there. He never lost his cool, but—

"Tōshirō; freeze my arm!"

Wide-eyed, her captain did, swinging Hyōrinmaru forward and coating Isshin's entire arm in a thick layer of ice. His grip loosened enough for Rangiku to pull herself free; she landed back on her feet and took a big step away.

"Interesting, but ultimately pointless," Zommari said. "Each of Brujería's eyes can command sovereignty of its own entity." Another of the eyes opened—Rangiku lost the feeling in her right leg.

Her eyes went wide as she was pulled forwards against her will. "No, no, nonono," she said, fear forcing her pitch higher on each word. There was something unspeakably terrifying about parts of her body moving against her own will. Her right arm went next; she used her left to snatch Haineko's hilt away before Zommari could use it.

A crashing sound and another sizzling blast of hot air clued Rangiku in to the fact that Isshin was trying to attack before they were overwhelmed. She could feel Tōshirō's reiatsu, too—probably they both were, but…

Zommari was pretty hard to damage, and it seemed like they were running out of limbs to fight with. No sooner had she thought it than another eye opened. She swore it was looking right at her face.

" _Bakudo #81: Dankū_!" she shouted. It was the first thing she thought of.

The clear barrier appeared between herself and Zommari. Not more than half a second later, a large black sun-shape appeared on the surface; Rangiku breathed a sigh of relief. It was short-lived, however—her own hand clapped over her mouth in the next moment, quickly stifling any thoughts of using more of Tessai's kidō lessons.

Still, she thought she had an idea now. Hoping that the other two could figure it out as she went, Rangiku used the hand she had left to stir Haineko's ash back to life. Trying to remember which eye held her right hand, she smothered three of them at once in the ash, jerking her wrist to cut with it.

Luckily for her, it looked like the eyes were weak points on Zommari's body—just like anyone else's. The feeling came back to her other arm, and she dropped her hand from her mouth. "Just blind the eyes—it's kidō!"

She didn't have to tell them twice. Ice, fire, and ash all swirled around, filling the room to the brim with a thick cloud of steam and smoke that made it nearly impossible to see anything. Guiding Haineko to the ceiling, Rangiku used her to hem in the powerful elemental attacks of both her current and former captains. As one, they dropped the reiatsu cocktail directly on top of Zommari—smothering him in it.

Isshin darted in for one last hit, drawing Engetsu in an iaijutsu move that left the Espada, blind and reeling, with a brand-new split down his middle. He burst apart, dissolving into reishi, and Rangiku breathed a sigh of relief.

"I thought that'd never be over," she whined, slumping to the ground. She was completely drained and really needed a healer… but she was alive.

Tōshirō scowled, Isshin grinned, and her world felt exactly how it should be—just for a moment.

* * *

"All right, Akon; how are things looking on your end?"

The rapid clack of keys accompanied Kisuke's question; he entered the data from Karakura Town with easy surety. He'd long ago mastered kishi-reishi conversion; all this really required was the same thing on a larger scale. He hadn't told Yamamoto that, though—better that this seem like it put him out. For a lot of reasons.

Still, knowing what to do and doing it were different things; all the confidence in the world was pointless if he input anything carelessly or messed up his calculations.

"Looks good; I'm sending you the readings from the replica now."

Given that Mayuri and his vice-captain were both in Hueco Mundo at the moment, Akon was the highest-ranking member of the Twelfth left. That suited Kisuke just fine; they'd worked together back in the day—he didn't have to waste time explaining himself and trying to get anyone to believe him.

He liked—needed—to keep people around him who were skeptical of the things he said and did. But sometimes, what was called for was decisive action; compliance made that significantly easier.

The data from Soul Society popped up in a window on his screen—Kisuke scanned the numbers. He made a little hum of satisfaction in the back of his throat and copied the information over; now that he had the parameters and the calculations, actually casting the kidō wouldn't be too difficult at all.

"Got it, thanks. Let me go get this set up. We'll be able to finish the swap in about ten minutes." Impatiently, he tossed his head, flicking several bothersome strands of hair out of his eyes.

"Sure. We'll stand by on this side."

Nodding absently, Kisuke ran his eyes over the numbers one more time, committing them to memory. Reaching to the side, he grabbed his hat off the table and dropped it onto his head. Hooking his fingers over Benihime on the way out, he slid open the door to his room.

"Yoruichi! Tessai! Time to go!" Thankfully, they had a fourth person in town perfectly capable of casting a kidō of this level—and Hachi wouldn't mind helping them half as much as most of his friends.

"Hachigen is ready at the north pillar," Tessai said, correctly interpreting Kisuke's expression.

"Excellent. Tessai, you take the south. I'll go west, and Yoruichi can get the east one. We'll cast on my signal."

Both of them nodded—there wasn't much time for anything else. Aizen could attempt to invade the Jūreichi at any moment. It was important that he didn't succeed, else the rest of this would be for nothing at all.

* * *

"Heh. You look like someone chewed up your face and spat ya back out."

Kenpachi shook his head to clear his vision. It was gettin' all weird and blurry at the edges. Probably somethin' to do with all the blood he'd lost. He was telling the truth though—Grimmjow didn't look too pretty right now. One of those kendo moves the old man had forced him to learn had caught the Arrancar under the eye, dragged down to his jaw, skipped a few inches of air and then dragged some more along his chest. Plus the other random cuts and shit that probably neither of 'em remembered giving or getting.

"You ain't doin' so well yourself, Zaraki."

And that was the damn truth, wasn't it? His uniform was gone from the sash up; all the skin there was hashed into ribbons by those claws. Most of 'em were shallow marks, but a few of the good ones had cut nice and deep. What was most surprising was that he was about outta reiatsu.

They were both in probably the shittiest shape of their lives—and both of them were grinnin' like a couple of idiots. When Kenpachi won this, he hoped he didn't accidentally kill the guy. That way he could come back and fight him again sometime.

They'd destroyed pretty much every inch of building anywhere around; the Kurosaki girl kept herself and Yachiru behind a shiny pink wall. Probably a kidō. That was good. It had held up to a lot, bein' this close to them. That meant he didn't have to hold back on the last strike.

'Cause this would be the last one, for both of 'em. He knew it—and Grimmjow knew it too, from the way he was wielding those long claw-things of his. Des-something, he'd called it.

"You ready?" He asked, adjusting his kendo stance until it felt right.

Grimmjow gave a little jerk of his head, and both of them bounded forward.

Kenpachi swung as hard and as fast as both hands would allow. Grimmjow surprised him—instead of jumping all the way in one go, he hurled himself forward and pushed off the ground with one of his hands, twisting his body out of the way of the blow. His free hand got right in at Kenpachi's ribcage. Kenpachi brought the hilt of his zanpakutō back hard—the bones in Grimmjow's hand snapped.

But the damage had already been done.

Kenpachi fell first, blood leaking onto the ground like someone had left a fuckin' faucet on. He wasn't dead—he'd survive this, if Kurosaki was half as good as he figured. But he'd been beaten, that was for sure. A second thud came after; that was probably Grimmjow falling over just the same.

With a grunt, he rolled over onto his back. Kenpachi coughed, bringing up more blood; the taste didn't bug him, though. It was pretty normal. He smiled, blood and all. "We should do this again somet—"

" _Bakudō #39: Enkōsen_!"

A barrier appeared right in front of Kenpachi's face. He heard the heavy whistle of something big moving really fast through the air. With a sound like grinding glass, the shield shattered. He raised his mangled arm to block—

A crescent-shaped blade sliced right through flesh and bone. Kenpachi's lungs stopped as it dug a hole in the middle of his chest, crushing everything in his ribcage.

The world went dark.

* * *

Uryū felt something change in the area—someone's reiatsu dimmed, then disappeared entirely. It was as though a candle had been snuffed; whatever was preventing him from pinpointing locations with accuracy also stopped him from identifying whose it was. It could have been anyone. An Espada, an ally…

A friend.

"Hey, did you…?" Karin's tone was laced with a thread of concern.

"Yes." He shook his head. "We have to keep going."

Whoever it turned out to be, they had to keep moving forward. Their best chance of finding Yuzu still lay in making it to the center of this place. That was what they'd come here to do. Swallowing thickly, Uryū returned his eyes to the front and pushed himself forward again with _hirenkyaku_.

He thought this might be the entrance to the main building. At least, it was bigger than the rest of them, and central—the long staircase leading up seemed to lend a kind of gravitas to it as well. White stone, barely touched with shadow, stretching out steeply before them. At times, he swore it was some kind of optical trick—though he could feel each new step, they hardly seemed to be making any progress at all…

…until they abruptly reached the landing. From the soft noise of surprise Karin made, it was just as sudden to her as it was to him.

Uryū's attention was immediately drawn forward. The space was large—it was mostly an open area, punctuated by smooth columns. The roof they supported cast the floor in deep grey shadow; it managed to seem both dark and empty.

But standing in it were two Arrancar.

"You!" Karin brandished Hisaku at both of them. "You took Yuzu! Where is she?!"

The one on the right—a particularly large man with the remnants of his Hollow mask on his chin and jaw—pulled his mouth to one side, half-grinning. The other was considerably shorter and thinner—his expression didn't change in the slightest.

"She is beyond your reach," the small one said tonelessly.

"Oh yeah? We'll see about that." Karin glanced sideways at him. "Stand back, Uryū. This is gonna be messy."

The taller Arrancar cracked his thick knuckles, taking a step forward so that he was in front of the other. "Sounds like fun, little girl."

"Are you sure about this, Karin?" Uryū didn't much like the idea of leaving her to deal with any part of this on her own.

But she nodded. "Trust me. I've got this. Go find Yuzu."

He doubted it would be so simple as that, but he did concede the urgency. He stepped past her on a reishi current, veering around both of the other two—

A glimmer from the corner of his eye was all the warning Uryū had. He raised Yorugen to meet it, knocked sideways by the force of the blow. Landing softly on his feet, he turned to the right. The smaller Arrancar had followed him; on the one hand, he was relieved that left Karin with one opponent instead of two. On the other…

"Stand aside," he said. "I'm not here to kill you." All he wanted to do here was get his friend back.

"That is unfortunate," the Arrancar replied flatly. "Because if you do not, you will never make it past this point."

* * *

Yuzu flashed to the left, making space for Yachiru to jump in and hit. The Eleventh's vice-captain glowed with bright pink reiatsu—Yuzu was working around her more than they were really working _together._

But… she could understand that. Everything had happened so quickly. Grimmjow and Captain Zaraki made their last go at each other. Both of them survived—and seemed pretty okay with it. She'd been about to breathe a sigh of relief and start healing when she'd noticed Nnoitra's reiatsu.

She'd thrown up a shield in front of Zaraki-taichō—the only thing she _could_ do at that distance. But it had been too weak to stand up to Nnoitra's massive swing. So had the captain's arm. And then—

Then he was gone, just like that.

Her effort to save him had meant nothing. Achieved nothing.

And Yachiru—Yuzu had never expected anything like this. She was flinging herself over and over again at Nnoitra, trying as hard as she could to cut him, but even the strikes of the creatures her shikai created couldn't pierce his hierro. It was all Yuzu could do to try and protect her while she made the effort.

" _Walls of iron sand, a priestly pagoda, glowing ironclad fireflies._ " Hasuhime braced against her shoulder, Yuzu clasped her hands together. Pinkish orbs drifted upwards from where her knuckles met—five in total. " _Standing upright, silent to the end!_ " Bending her knees, Yuzu struck the ground with her combined fists. " _Bakudō #75: Gochūtekkan!_ "

The orbs extended into large pillars, linked together near the top with chains, and crashed down atop Nnoitra. That might hold him a little while, but she wasn't sure—

"Yuzu." Grimmjow didn't really have the strength for shouting, but his voice carried to her anyway.

Grimacing, she glanced at Yachiru. The vice-captain's anger and grief showed no signs of abating—already, she was hacking at the kidō, trying to reach past the bars to Nnoitra. But it held, at least for the moment.

Flashing to Grimmjow's side, she lit her hands with kaidō. He reached out; the hand that wasn't completely shattered closed over one of her wrists. "You don't have time for that. He's gonna be outta there faster than you can heal me."

"But—" If Nnoitra was willing to murder an injured person like that… she couldn't trust that he wouldn't do it again.

"I said it ain't gonna help!" he snarled; Yuzu swallowed, but did not flinch back. He released her hand, reaching into one of his pockets and handing her a small cube of some kind.

"What is—"

"It's called _Caja Negación_. Get it inside his Hollow hole. It'll buy us some time."

Yuzu took the small cube in unsteady hands, but nodded. Time was really important right now. If Nnoitra got even one good hit in on any of them… "Where?"

"Eyepatch."

Pushing out a breath, she nodded again. "Thank you, Grimmjow." Taking a few steps back from him, she rested one of her hands on the pole of her zanpakutō, muttering another incantation.

" _Bakudō #81: Dankū_." It was the most powerful shield in her repertoire; she curved the wall shape into a dome and set it down over him. Hopefully… hopefully that would be enough, if Nnoitra turned his attention this way.

A loud, shuddering crack drew Yuzu's attention—Nnoitra was fighting his way free of the _gochūtekkan._ The pillars trembled and burst apart. Yuzu swung Hasuhime up into a blocking position by sheer instinct; it probably saved her life.

Nnoitra's massive double-crescent polearm screeched against the shakujō's pole. "Oh, you've done it now, little mouse," he said, lip curling into a sneer. "All your protection is gone—there's no escape this time."

He bore down with his body weight; he was so much taller than her that his frame could practically bend over hers, blocking most of her field of vision. She could hardly see anything but him. Her arms quaked as she tried to fend him off, to escape the lock—anything, as long as she could keep him _away_ from her.

Nnoitra chuckled, low and rolling; his sneer stretched into a smile. "Are you scared, little mouse?" The very edge of one of the blades on his weapon brushed over the skin of her throat. He was close enough she could feel his breath on her face.

Of course she was afraid. She knew he knew it.

" _Hadō_ —"

"Zu-chan!" Yachiru appeared over Nnoitra's shoulder.

"Yachiru! Cut off his eyepatch!" Yuzu used the momentary distraction Yachiru provided to disengage, stepping out from under the pressure of Nnoitra's strength. Her arms burned from how much effort it had taken to even hold Hasuhime against that strange weapon—the rest of her shook for another reason entirely.

Yachiru didn't ask why—she just did it. Nnoitra leaned away from the blow, but the third strike from the vice-captain's shikai nicked the patch covering his eye, and the fabric fell away.

Grimmjow had been right—there was a Hollow hole right where his eye socket should have been. Yuzu aimed her toss as well as she could, throwing the _Caja Negación_ right for the spot. The second it entered the empty space in Nnoitra's head, there was a surge of reiatsu, warping and twisting outward from the spot.

Nnoitra glared at her venomously. "When I get out of this, mouse—"

But the words were cut off; the reiatsu closed in around him and his disappeared. Yuzu fell to her knees on the ground, panting. Sealing Hasuhime, she slid the tantō up her sleeve and ran both hands down her face. Time, she had time—but how much?

Grimmjow. He had to be her priority now. Yuzu stood, staggering over towards him. If she could heal him before Nnoitra came back, then—

"Kurosaki-kun." The voice, mellow and sweet, was wonderfully familiar.

Yuzu turned, her hand still resting on the _dankū_ 's semitransparent surface. Her shoulders slumped; she breathed out a relieved sigh. Trying to smile proved more difficult; she found that she simply couldn't—not considering everything that had happened here.

"Unohana-taichō."

* * *

"Would ya lookit that. They made it right t' the front door already."

Gin wore the usual smile, but Sōsuke was not oblivious to the fact that his shoulders held an abnormal tension in them. That was to be expected, of course—the fights on the monitors had been quite close, for the most part. It was too bad Zommari hadn't amounted to more. Watching his former vice-captain hurry to the scene of his only friend's battle might have been quite entertaining.

But there was time enough for such things yet. Sōsuke's eyes flicked from one monitor to the next, scanning all of them with a practiced eye. Rukia Kuchiki was almost back on her feet—though quite weakened from her confrontation with Aaroniero. _That_ one had made for particularly interesting viewing. The little Tenth Division unit was moving—slowly, due to extensive injuries to the young captain and his second-in-command.

Grimmjow and Zaraki had made quite the spectacle of themselves—though as expected, an opponent with more than brute strength had proved troubling for a captain who only had one skill. The result would have likely been quite different if the match had been with Nnoitra, who was mere brute force himself. But that was beside the point, now. Nnoitra's complete lack of mercy had served its purpose—and amusing as it was to watch Kusajishi and Yuzu try to hold him off, the arrival of Unohana did present something of a conundrum.

"Starrk. Please go retrieve our guest. I do believe she has been permitted to wander a little too far astray. And remember not to tarry. Time is, after all, of the essence."

The Primera's reiatsu disappeared without so much as a by-your-leave; Sōsuke smiled to himself. The remaining screens were just as interesting—Szayelaporro was about to meet his match, it seemed. Yammy had the other Kurosaki on the defensive; the release of her bankai was no doubt imminent. Useful data to have, for those that remained in the room.

And Ulquiorra appeared to have tied himself up in a match with the Quincy. How intriguing. Even Sōsuke wasn't sure how that was going to end. It was a shame he wouldn't be here long enough to see it in its entirety. Well… perhaps he would have some use for the footage at a later time.

"Aizen-sama."

Sōsuke resisted the urge to sigh. "Yes, Kaname?"

It wasn't like he didn't already know what was bothering him; but politeness did make demands. He made a point to answer them when possible.

"It is obvious that Grimmjow had betrayed us. Will you not permit me to exact justice upon him?"

If Sōsuke killed every traitor or disobedient soldier in his army, he wouldn't have much of an army _left_. "That will not be necessary," he replied mildly. "Grimmjow has served his purpose well enough—there is no need to waste the time."

"But—"

"Kaname." Sōsuke allowed his tone to sharpen just fractionally; the other man fell silent. "If you are feeling bereft of something to do, please go prepare the garganta. We will be departing before long."

"Of course, Aizen-sama." Kaname's uniform rustled as he bowed.

Sōsuke paid him no further mind. Once Starrk returned with Yuzu, he could finally move things into their last phase. For nearly two hundred years, his ambition had been the same—and finally, he was on the cusp of realizing it.

Only one significant obstacle stood in the way.

But it would not stand for long.

* * *

 _Term Dictionary_ :

 _Brujería_ – 呪眼僧伽 – The kanji are "Sangha of the Bewitching Eyes," while the Spanish is just "Witchcraft." Zommari's resurrección, which allows him to steal the "sovereignty" of whatever the (50-ish) eyes on his body look at. Which is like way scarier when you don't have a bazillion tiny little blades as your weapon.

 _Dankū_ – 斷空 – "Splitting Void." Bakudō #81. Creates a defensive wall to block enemy attacks. It's capable of defending against spells up to Hadō #89. Rangiku spent a month learning a few useful kidō from Tessai—this is the payoff. Yuzu, being pretty much a kidō specialist at this point, can also use it.

 _Gochūtekkan_ – 五柱鉄貫 – "Five-Pillared Iron Weights." Bakudō #75. The practitioner clasps their hands together, forming five small yellow orbs between their clasped hands, which move above the practitioner's head before forming a circle. Raising their hands above their head, the practitioner slams them downward. A bright light is generated in the sky above the intended target, and five tall pillars—connected to each other by chains—pin the target to the ground.

 _Caja Negación_ – 反膜の匪 – The kanji are "Anti-Membrane of Negation." The Spanish is "Negation Box." It's a cube-shaped device used to isolate and trap the target in an alternate dimension. Intended for the Espada to use as punishment if one of their underlings stepped out of line. In canon, Grimmjow used his on Ulquiorra to make him go away for a while so he could fight Ichigo uninterrupted. It got repurposed here, obviously.

* * *

Uh… yeah. So that happened. Please don't kill me; I know Kenpachi is popular. I like him too, but I think his death is a pretty realistic consequence here. He had a tough match with Grimmjow, and Nnoitra's an enormous douchenozzle who has no reason _not_ to finish him off. And the rescue just isn't going to come on time, every time. Plus if I only killed off unpopular characters, the danger wouldn't be nearly as real, right?

…erm.


	16. Chapter Sixteen: The Rise

_Content Warning:_ Violence, minor character death.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Sixteen: The Rise

* * *

Retsu swept her eyes over the scene; her face remained set into a neutral expression. It was not difficult to discern what had happened here. She could still feel the lingering traces of Kenpachi Zaraki's reiatsu—the depression in the sand where he had fallen remained, soaked red in more than one spot.

Exhaling softly, she turned to Kurosaki-kun, who stood protectively over what looked like an altered _dankū_ barrier. One of her palms rested on it, but she'd placed most of herself in between the shield and Retsu. Unconsciously defensive of the person inside it, then.

Next to the indent in the sand, Yachiru fell into a sitting position. She didn't look at anything but the largest of the irregular stains.

"Um, taichō?"

Retsu's attention returned to her ninth seat. "Yes, Kurosaki-kun?"

"If it's okay… will you help me heal him? He… he saved my life." She pushed down on the _dankū_ ; it dissipated at the touch. Underneath it was a heavily-wounded Arrancar. His reiatsu was weak, but it flickered and crackled like an electric current.

"Of course, Kurosaki-kun." Strictly-speaking, it was more than possible that over a month in captivity had left Kurosaki incapable of making accurate judgements about who was a friend and who was not—but Retsu had the sense that this had not occurred here. Besides, she'd caught the last few seconds of the confrontation with the tall Arrancar; it was clear that whatever device had banished him was of their own creation.

Retsu approached the fallen Espada, assessing his condition. His injuries did not appear to be fatal; nonetheless, it would be best if he received treatment as soon as possible—if for no other reason than to prevent infection. Kurosaki was already crouched at his side. The Arrancar's lips were pulled back from his teeth in a silent snarl; beyond that he gave no indication of pain. Indeed, the way he tracked her movements was interesting to Retsu—there was a certain wariness there, one that he did not turn on Kurosaki.

Convinced, she smiled mildly. "The other one… he will return to the field soon?"

The Arrancar jerked his head in a nod, but it was Kurosaki who replied.

"Yes, taichō. I'm not sure exactly when, but—"

Retsu's eyes narrowed at the same moment Kurosaki cut off her own thought. She turned, putting herself between the newcomer and her apprentice. This one was not injured—and from what she could sense, his reiatsu was formidable. He stopped a respectable distance from them, glancing at Yachiru for all of a moment before returning his attention to them.

"Yuzu," he said quietly. His body language was nonthreatening—he kept his hands in his pockets, and attempted to move no closer.

Retsu knew quite well that such things meant little, when one was capable of moving as quickly as he surely was.

"Starrk-san." Kurosaki showed no sign of distress at the presence of the newcomer. In fact, her expression actually eased for a moment, as though she were relieved about something. It quickly fell back into a frown, however. "He wants me back, doesn't he?"

The Arrancar nodded. His eyes slid to Retsu. "You should know that your sister and your friend are close to the center. I don't know exactly what he plans to do if we don't comply, but…" He trailed off, leaving them to fill in the blanks themselves.

"Kurosaki-san and Ishida-san both came to this place quite well aware of the possible consequences," Retsu said mildly. "If we are all so much at Sōsuke Aizen's mercy here, perhaps we should force him to demonstrate that fact." Retsu's hand drifted to Minazuki's tsuka. She kept the touch feather-light, but her eye contact with the Arrancar was direct.

"I don't want to fight you," he said bluntly. "But you don't want to force this, not here and now. The better half of his army is still fresh—I think you know what they could do to your team."

"Fuck 'em," growled the injured Arrancar, trying to push himself up into a seated position. "I'll fight 'em all myself."

"Grimmjow-san, please don't move," Kurosaki protested, forcing him back down with firm hands.

He grumbled, swearing under his breath—but he complied.

"We don't have a lot of time," the one called Starrk said. "I really hate stuff like this, but I've got to take you back, or chances are everyone dies."

Retsu heard an unspoken _including you_ on the end of it, and tilted her head thoughtfully. Half-turning to face Kurosaki, she folded her hands in front of her. "Only you can fully appreciate the circumstances of this decision, Kurosaki-kun," she said. It was very clear that there was much at play here that she did not wholly grasp yet. "Therefore, the best person to make the decision is you. But understand that if you do not want to return, you do not have to. Everyone here has already agreed to that by coming to retrieve you."

Kurosaki looked torn, pulling her lower lip between her teeth. It was a tic Retsu was quite familiar with. "I… you said Karin and Uryū are close to where he is?"

Starrk nodded.

Carefully, Kurosaki let her kaidō fade out and stood. "Taichō, Grimmjow-san. I'm sorry but… I think it really is best if I go for now. I don't know if… the rest of the Gotei 13… they're planning to meet him somewhere else, aren't they?"

Retsu dipped her chin. "They are." And strategically, it was indeed sounder to turn the second half of his army on those prepared for their arrival than the already-injured group here. Kurosaki's obvious train of thought was admirable. But it was also extremely risky to herself.

Visibly bracing herself, Kurosaki swallowed thickly and curled her hands into fists. "Then… I guess I'll be seeing you later," she said softly. She bowed to Retsu, offered a grim smile to her Arrancar friend, and cast a worried look at Yachiru.

"I will take care of things here, Kurosaki-kun," Retsu assured her. There was no need for her to worry about this much, at least.

"Thank you, taichō." Squaring her shoulders, Kurosaki approached the Espada. She tipped her head up to meet his eyes, stepping in close enough for him to pick her up off the ground without trouble.

He held her, Retsu noticed, very gingerly.

Half a second later, they were gone, and she returned her attention to the partially-healed man on the ground. Grimmjow, as he was apparently called, had pushed himself back into a mostly-seated position. Retsu frowned slightly.

"It was the other that killed Kenpachi Zaraki?" she asked softly.

He narrowed his eyes at her, but grunted an affirmation. "Yeah. We fought; fuckin' Nnoitra finished him off like a coward."

"I see. And when he returns, it will be to this place?"

He shrugged, wincing when the motion pulled at something. "Dunno for sure, but probably."

"Very well, then." Retsu knelt beside the Espada, intent on finishing what Kurosaki had started.

"You ain't gonna kill me?"

Ah. Apparently he was not so foolish as to believe that Kurosaki's mercy guaranteed Retsu's. Astute, if misplaced at the moment.

"You have done something to earn the regard of my ninth seat," she replied simply. "In the absence of evidence to the contrary, I will not consider you an enemy of mine."

He cocked his head at her. "And if there was evidence? What then?"

Retsu's smile inched just slightly wider. "I would destroy you."

"Heh." He let out a breath, relaxing back onto his forearms while she worked. "Sounds like fun. But I guess shit's serious now." Grimmjow's eyes narrowed; his mouth dropped into a scowl.

"It seems that it is," she agreed.

* * *

"Yuzu. We missed you."

She swallowed past the lump in her throat. For the moment, it was only Aizen in front of her; that was absolutely no comfort at all. Starrk's presence behind her was more reassuring—it had a palpable solidity to it, like he was going to stay there. Yuzu bit her lip.

Aizen drew the Hōgyoku out from its usual spot, but… something felt different. Passing the object into his left hand, he pressed a switch on the inside of the column, moving a different part of it away. From that, he drew out— _another Hōgyoku_? It looked almost identical, except that maybe it was more blue than purple.

It felt completely unlike the other, though. It wasn't reiryoku, exactly—more like… reishi? Lots of it, packed together but humming like it might vibrate apart at any moment. She wondered if it might not be unstable. Despite her suspicions, though, it didn't burst into pieces at Aizen's touch, though the surface did crackle and snap. That was different, too—the other one slowly oozed, like it had to be convinced to move at all.

"Your puzzlement is understandable. Kisuke Urahara created his Hōgyoku in a different way than I made mine. Yet they are fundamentally similar all the same. Two halves of a whole, one might say."

Halves? Yuzu's eyes narrowed thoughtfully. If it wasn't yet complete, then…?

"Now… if you would please continue the restoration of this one…" As usual, Aizen handed her the purple Hōgyoku.

Yuzu cupped it carefully in her palms, suppressing a shudder. It was a terrible feeling, holding this many parts of souls in her hands, knowing that the reiryoku that comprised this little sphere had been shorn from living people. Lifting her eyes to Aizen, she awaited his nod. When he gave it, she shifted the orb to her left hand and released Hasuhime with her right.

 _What are you going to do?_

The spirit's question was reasonable. She held half of Aizen's not-so-secret weapon in her hand. But if she just tried to abscond with it, he'd cut her down with neither hesitation nor difficulty. If she refused to mend it… Yuzu licked her lips. It wouldn't be her who died for such disobedience, she knew.

And Starrk's continued presence at her back made much more sense then. She'd thought it strange that Aizen had allowed him to stay; after all, Starrk had just let her leave with Grimmjow. There was no way Aizen would have believed an excuse about being asleep.

It seemed that they were hostages for each other. That tipped the scales for her.

 _Help me, Hasuhime._

 _This is a dangerous decision, Yuzu._

 _Every decision is dangerous right now. This is the only one I can live with._

 _As you wish._

Yuzu's hands lit with the pale light of a restoration kaidō; she had to concentrate carefully to maintain the steadiness of the reiatsu flow. Her heart was pounding in her chest; she swore she could hear it. But she forced her limbs to be steady, her face to be neutral. Slowly, the last traces of instability and corruption disappeared from the Hōgyoku. The tiny pits in its surface smoothed over to something like perfection.

When she was sure it was done, she let the light of the kidō fade out.

Aizen took the orb from her grasp; she relinquished it without a fight, taking a large step away. She stood close enough to Starrk that she could vaguely feel his body heat on her back and shoulders, small solace though it was. She watched Aizen examine the orb, smoothing his thumb over the surface. Apparently satisfied, he brought the other to it.

The moment they made contact, there was a ripple in the room's reiatsu. It felt small at first, like a drop in a pond, but it swelled until it was difficult to detect anything else. A hand on her shoulder tore Yuzu's attention from the fusing spheres. Starrk bent down to speak quietly in her ear.

"Run."

She twisted to look up at his face. The expression he wore was completely serious; his eyes flicked towards the door.

"You come, too," she said. Maybe… maybe now that Aizen had no use for her anymore…

He shook his head. "If he sends someone after you, I want to know. Find Ulquiorra."

Yuzu's hands curled into fists; his thought wasn't incomprehensible. Besides… the loss of her might not matter, but he was an Espada. He probably counted enough to be pursued. Without the time to think it through or try and convince him, Yuzu did what he'd asked—

She ran.

* * *

Air whipped by Uryū, dragging angry fingers over his uniform and his hair. He struggled to pull in a breath—the Espada had hit him hard enough to knock the air from his lungs. He was glad for the reishi armor, which had probably stopped the blow from cracking his ribs. As it was, he'd been tossed out the side of the landing; he pulled reishi under his feet and jumped off of it, ascending. At least if the Arrancar had to follow him out here, there would be more room to maneuver.

He threw himself sideways in just enough time to avoid bisection by sword, twisting in midair so that the next attempted blow landed right at the intersection of Yorugen's crossed blades. For someone built so slightly, the Espada was nearly unbelievably-strong; this close, Uryū knew that his reiatsu levels were the reason.

Shifting into _Kage-e_ , he used the moment of surprise to his advantage, drawing the blade of his shadow across part of the Arrancar her could reach—the achilles tendon. His reiatsu was sharp enough to pierce his opponent's hierro; they jumped apart. Uryū swapped places again so that his corporeal body became solid, flicking blood off Yorugen.

It wasn't exactly surprising to see how little there was, but it certainly wasn't encouraging, either. Clearly, the Espada's ability to regenerate damage kicked in quickly, and was much more potent than that belonging to any ordinary Arrancar. So far, they had been testing each other; that much was clear. But to what end? Shouldn't this person want to kill him as quickly as possible?

"You are Uryū Ishida," he said, fixing Uryū with an unblinking stare.

Uryū's brows descended over his eyes, creating a furrow. "I am." There was hardly a point in denying it—the Arrancar spoke with certainty.

"You are here to save Yuzu Kurosaki."

Not 'to kill Sōsuke Aizen.' It was the truth, but…

"Yes."

For the first time, his foe closed his eyes—he held them so just a fraction longer than a person usually did when blinking. "What then?"

Uryū's lips thinned; he shifted his grip on Yorugen, squeezing the hilts for a heartbeat before easing his fingers again. "What do you mean?"

"If you managed to recover her. What would you do then?"

 _Why bother asking_? He was tempted to inquire, but for the moment, he held off. "We take her back to Soul Society, of course."

"Do you imagine that will be safe, when Aizen is through with the Gotei 13?"

No honorific. Just 'Aizen.' Uryū recognized that this meant something—but he had no idea _what._ The Arrancar did not give him the time to formulate a response. Instead, he rushed suddenly forward again, his zanpakutō moving so quickly though the air that it blurred.

Uryū caught the blow on one of Yorugen's hooks, twisting to trap it there and pivoting to kick for the Arrancar's midsection. A painful metallic scrape issued from the parting blades as the other man yanked his free, moving clear of the blow in plenty of time.

Uryū let his grip go slack on both blades—their fully-enclosed handles meant they remained around his hands as he formed his bow, hanging straight down without impeding his draw. Channeling the reishi, he loosed a volley of projectiles, tacking a Seele Schneider on at the end.

The Espada cut most of them down in the air, but elected to avoid the larger arrow; the disadvantage to their current height was that Sprenger was not an option without a surface to form the pentacle on. He considered trying to herd the Arrancar elsewhere, but he was so mobile by comparison to the average opponent that Uryū doubted he'd ever stand in one place long enough for the technique to be viable.

"This is a waste of time," the Espada said dully. "And I do not have it to squander." He pointed the end of his sword at Uryū. " _Tozase, Murciélago._ "

The blade burst apart in a flash of green energy, rising only to fall again—almost as though it were rain. Uryū stepped outside the area of effect, just to be sure, drawing back another arrow and firing. Despite the distraction of the release, the Espada's arm snapped up, effortlessly catching the reishi bolt in mid-flight. His hand flexed; the arrow shattered into particles.

Uryū grit his teeth. Either he was in for a long fight…

Or a very, _very_ short one.

* * *

This guy was _huge_!

At first, he'd been big but still kinda human-sized, but as soon as he'd let his release thing go, he'd probably gotten twenty times bigger. Karin, never a tall person, was no longer concerned about that—he'd have made _anyone_ look puny by comparison.

She looked down at Hisaku, then back up at this Yammy guy.

"What's the matter, little girl?" His voice sounded like thunder—she could hardly make out the individual words, he was so loud. "So scared you can't move?"

Not fucking likely.

Tightening her doublehanded grip on Hisaku, Karin dug deep into her well of reiryoku, drawing it out and channeling it through the blade. "Ready?" she murmured.

 _Of course._

Slowly, she pulled in a breath. Time for a field test. "Bankai. Keizen Hisaku!"

The reiatsu that she'd been compressing along Hisaku's blade erupted, covering her in red fire. It didn't burn her—that much she was grateful for. The chain holding the feather on the end of Hisaku got longer; the feather itself became a tessen, copper-colored and metallic. She gripped it in her free left hand. The katana's blade turned red, like she'd stuck it in a forge; the slight weight of a scarlet haori settled over her shoulders.

The majority of the energy from the release itself concentrated behind her, stretching outwards from her shoulderblades. She wasn't great at flight control yet, but the wings had other uses. Like the one she was about to try.

Flapping them forward with a sharp motion, Karin released several red spears of energy; the same force launched her into the air. She didn't like her chances of being able to accomplish much from near his feet; Yammy's hierro was no joke. Supposedly, this guy was the Décima Espada—but with this much reiatsu, it didn't really matter. He was going to be hard to kill.

Her projectiles crashed against the ankle area of one of his many legs—Karin grimaced when the explosive hits didn't leave so much as a scratch on him. His response was to fire several bala at her in quick succession; Karin folded the wings in front of her like a shield, letting the hits bounce off.

The obvious sound of a _cero_ charging reached her ears; she wasn't going to be able to shield herself from that. Shifting her grip on Hisaku, she raised the zanpakutō as the red blast came crashing down, swinging forward to meet it.

The katana was covered in reiatsu, packed in as densely as she could force it—that was the reason it changed color. Her swing threw an arc of compact energy, parting the cero up the middle and splitting it away from her. She couldn't block or divert it outright, but in this case, being small was an advantage—she only had to mess with the trajectory a little bit and she could avoid the hit completely.

When the last of it fizzled out, Karin gritted her teeth. "My turn," she muttered through them.

Raising the tessen, she spun herself around a full rotation, flinging a blast of fire from the end. It wasn't nearly as wide as his _cero_ —but it was wider than she'd meant it to be, and she cursed when it detonated earlier than she'd wanted it to. Even without the full force, though, it left a burn on Yammy's shoulder; a blistering patch of red skin.

He looked down at it, face twisted up in a snarl. "You think you're gonna take me out with shit like that? Don't make me laugh, little girl!"

Karin scowled. "Don't get your panties in a knot, asshole. We're just getting started!" Her fingers tightened on the tessen and katana both—she didn't have time for this. Yuzu was still in there somewhere, and Karin had to find her.

* * *

Sōsuke watched her run from the room with a dull surprise.

The interesting thing was not that Starrk had advised her to leave. It was that she'd actually _done_ it. He still, after all, had control of the Arrancar army, and now the Hōgyoku was repaired. He moved his eyes back down to the fusing spheres. Reiryoku and reishi. Stability and fluidity. Order and chaos. The real power was in the synthesis—the reconciliation of opposites.

It no longer mattered that she ran. It was no longer worth the effort to punish her for it, either—the fall of everything she desired to protect would be punishment enough.

As for Starrk, well… he would not live so much longer that punishment was truly necessary. Now that this was done, such low-level matters were beneath Sōsuke's concern. There was one thing, however, that he still needed to do before they left this place.

"Starrk. Please retrieve Kaname, Gin, Anzparrejar, Baraggan, Wonderwiess, and Tier." He might have preferred to bring the full top half of his Espada, but by his calculations, the ones already named would be enough for their purpose. It also reduced the traitorous elements to two.

The Primera nodded slightly and left the room. Doubtless, he believed that remaining here and taking commands as usual was a protective strategy. People became so much easier to read when they grew attached to others. Everyone wanted something slightly different for themselves—but for the people they held dear, well, it was nearly universal: comfort, safety, happiness.

At Starrk's exit, Sōsuke removed an object from his pocket; it was the same device he'd used to extract the Hōgyoku from Rukia Kuchiki's soul. Now, it would serve the inverse purpose. Parting the fabric over his chest, Sōsuke pressed the device to the spot just under his heart. His very flesh gave way like water; into the spot he nudged the Hōgyoku. It was different now from how it had been then—the process was not entirely painless.

He felt it digging around under his skin, spearing in four directions with its unclassifiable energy. Blue-purple lines erupted from each cardinal side of it, dragging visibly over his skin; he was left with the orb partially exposed and a cross of discolored flesh. Something—a foreign weight—settled in the back of his mind, similarly to where Kyoka Suigetsu resided.

He felt something catch there, snag and tangle in the fabric of his thoughts, melding close enough to what was already present that the distinction between himself and the Hōgyoku blurred. It probed at his mind, at his soul—it sought to understand his will. Fortunately, Sōsuke's will had been the same for so long that it was not at all difficult to discern:

He was going to tear apart the weave of the world, and stitch it back together as he saw fit.

Sōsuke sensed the approach of those he'd summoned and smoothed his shirt back into place. His thoughts turned to what would next occur, and he felt the Hōgyoku's half-consciousness reacting to the newly presented information, scanning over it like a curious child. It wasn't, he thought, so entirely different from Wonderweiss—though perhaps with the addition of a capacity to learn.

Gin, Kaname, and the remaining Espada filed in, standing at attention before him. Sōsuke smiled benignly down at them, folding his hands behind his back. "Kaname, is the Garganta operational?"

"Yes, Aizen-sama," he replied.

"Good. It is time for us to depart for the Jūreichi."

Tier crossed her arms beneath her chest. "What is to become of the others?"

Sōsuke didn't so much as blink. "You will all, of course, be bringing your _fracciónes_ with you. As for the others… they will finish those that remain here." He waited three heartbeats for the inevitable question.

"The shinigami are acquitting themselves well. Is it certain that they will achieve this?"

The truth was that Sōsuke didn't _care_ whether they killed or died or both. He had no plans to return to Hueco Mundo as such after he left it. But. There was value in giving the query a reply.

His smile widened slightly. "You do have a point, Tier. Perhaps a little guarantee won't hurt. Anzparrejar. Remain behind and destroy all the remaining shinigami, please."

The Espada's eyes narrowed; Sōsuke could see the shift in his zukin where he frowned slightly. But he nodded nevertheless.

Starrk took half a step forward—perhaps to volunteer himself for the task instead, as if he'd ever complete it.

"Well now, that seems like a waste, don't it?" Gin tipped his head to the side. He turned, as if to leave the room, glancing back over his shoulder. "If that's the plan… then I'll be the one to kill them shinigami."

The blade of Shinsō was indeed exceptionally fast—at this point, Sōsuke did not believe he could have dodged it if he'd tried. His eyes widened slightly as the zanpakutō pierced his body; the accuracy with which Gin was able to wield it even without looking was quite admirable, truly.

Admirable, but not unexpected.

Blood welled from the wound as the blade retracted. Sōsuke raised his hand to the spot, feeling it seep through his fingers. He wondered if it was the last time he would bleed. "I knew," he said quietly, bringing his hand away from the wound and studying the dark red staining his flesh. "I brought you along, knowing your objective, because I was curious to see how you'd make your attempt on my life." He sighed. "But it's too bad for you, Gin. Do you think you can kill me—"

Gin, one sleeve completely shredded from being used to conceal the release, turned around to face him fully. Kaname moved to intercept him, but Sōsuke wasn't about to allow that; he stopped the other man with a fluctuation in his reiatsu.

"With somethin' like that?" Gin finished. "Nope." He held Shinsō out sideways, laying a finger on the middle of the blade. "Can ya see this? It's a missin' piece, right here."

Sōsuke squinted—he could just make out the absent fleck. A spike of pain shot through his chest; at first he thought it was the Hōgyoku, but the true answer snapped into place in his thoughts just as Gin parted his lips to speak again.

"I just left that piece inside ya."

Of course. It made sense now. How impressive—he'd never even suspected.

"Sorry for lyin' to ya, but my bankai ain't like I said. It don't extend as far as I said it does, or as fast. All it does is turn into dust for a second when it expands and contracts. And there's a deadly poison inside the blade that eats ya all up from the inside." His rictus grin stretched over his face. "Looks like ya figured it out. When I recalled it just now… I left a little bit behind in yer heart."

Gin took a flash step, arriving at a stop right in front of Sōsuke. Reaching out, he pointed right at the wound. "A hole's gonna open in yer chest, and yer gonna die. It's what I've always wanted, y'know." He touched the spot just above the wound. " _Korose, Kamishini no Yari_."

Inside Sōsuke's body, the blade fragment ruptured.

It wasn't even painful, feeling his own heart burst apart. The sensation transcended pain somehow—likely only possible because he'd actually survived it. Or perhaps it was the Hōgyoku, pressing in upon his consciousness and dulling the sensation. For though Gin held the physical object in his hand, Sōsuke still felt it in his mind, even as he fell to the ground. The hole in his chest was too large to cover with _both_ his hands—he had no doubt that if he hadn't just merged with the Hōgyoku, such a blow would have killed him.

Exquisite. If he need not even fear this anymore, then… there truly was nothing left to fear at all. Pain was not the only thing he'd transcended, it seemed.

"How unfortunate for you, Gin." Sōsuke spoke into the shocked silence, his wound already regenerating. "Even if it is not physically inside my body… the Hōgyoku that you have pilfered is already mine."

As he said it, Sōsuke called the Hōgyoku back to himself. It vanished from Gin's hand, reappearing in the hollow he'd carved in his own chest for it. Sōsuke drew Kyoka Suigetsu and stabbed forward in a single fluid motion. Gin would not recover so effectively from a wound directly to the heart. A line of blood dragged slowly down the length of the zanpakutō's blade, dripping to the floor just short of the tsuba.

"I must thank you, Gin." Sōsuke narrowed his eyes. "Without you, reaching this point would have been impossible." Bending his arm back, he withdrew Kyoka Suigetsu, letting the other man fall to the ground.

For a second, he contemplated the image. In a peculiar mirror of an earlier moment, Gin held his hand over his chest, staunching bleeding that would not truly stop. The wound was fatal, though it would be slow to arrive at its natural conclusion. Sōsuke elected not to hasten it. After all… this was a rather potent demonstration of something that all those watching now understood: the price of presuming to defy him.

"Of all the places to find treachery… it is discouraging to know it was so close all along." Sōsuke blinked slowly, making deliberate eye contact with each of those present, lingering last of all on Starrk. "Now come. We make for the living world."

Sōsuke stepped around Gin's kneeling form, but never once looked back.

* * *

 _Term Dictionary_ :

 _Murciélago_ – 黒翼大魔 – The kanji are "Black-Winged Great Demon." The Spanish just means "Bat." Ulquiorra's _resurrección_. Its release command is _tozase_ (鎖せ), the imperative of "to enclose" or "close in." It enhances all of Ulquiorra's combat attributes as well as granting flight and two abilities: _Luz de Luna,_ "light of the moon," which are the green energy javelins, and the _Cero Oscuras_ (黒虚閃), "Dark Zero" in Spanish, "Black Hollow Flash" in kanji.

 _Keizen Hisaku_ – 炯然緋鷟 – "Shining Scarlet Phoenix." Karin's bankai. The katana from the shikai doesn't change much in terms of appearance, except for the fact that the blade turns red-orange, a result of the reiatsu compressed along its length. Where the feather hung off the pommel previously, there's a long, relatively thin chain, which ends in a tessen-type fan. Karin's physical appearance alters as well: she gains an armored headpiece with feathers over her ears, a red sleeveless haori, and _kikko-kote_ (a sort of gauntlet with metal plates sewn onto cloth) in copper on yellow fabric. Plus, you know, wings made out of reiatsu. Those are helpful.

 _Kamishini no Yari_ – 神殺鎗 – "God-Slaying Spear." Gin's bankai. Capable of great speed and range, the deadliest aspect of the bankai is the poison in the blade, which activates upon the command _korose_ (殺せ), "kill."

* * *

I do apologize for the interval between this chapter and the last. Unfortunately, I've started school again, meaning that this will likely be a persistent problem. I will do my best to put out a chapter a week (hopefully on a consistent day that I'll figure out in the next couple of them). There isn't a _ton_ left to do in this story; my goal is to have it finished by the end of September or so. We'll see how that shakes out.

Also, I know that in canon Yammy is the Cero Espada. I have chosen not to do that. Really, I think he's less powerful than some of the others, and besides that his only real asset is brute force, which I tend to think ranks lower than other attributes. More importantly, I think _Aizen_ would rate it lower than other attributes. Honestly, the ranking system seemed messed-up in canon anyhow (and has been further messed up by character development in the AU), but it is what it is.

If the reasoning for some of the decisions the characters made in this chapter seems odd to you, I promise they all had reasons for doing what they did. If that doesn't help and you think I've massively screwed something up, do feel free to ask about it. I've tried to avoid _overexplaining_ the things people are taking into consideration; I acknowledge that this means I could be underexplaining instead. :/

Also, everyone: the awesome BiblioMatsuri has written more things in the CT-verse! You should definitely check out their story _for the fallen ones, locked away._ It's short, but great. :)


	17. Chapter Seventeen: The Fall

_Content Warning_ : Some graphic-ish depictions of violence and death in this chapter.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Seventeen: The Fall

* * *

Grimmjow shifted awkwardly; his wounds were gone, but he was bone-deep exhausted. That alone put him pretty much at the mercy of these shinigami. The little girl was still sitting near the spot where Zaraki had died—something about that made him uncomfortable, so he kept his eyes away from her. Given how much damage they'd done to the area, it meant that pretty much the only other thing of interest to be seen was Yuzu's captain. Unohana, she'd said.

She didn't look all that tough; but something about her was…

"Grimmjow-san, may I ask you a question?" Unohana kept her hands folded in front of her. She'd backed off as soon as she'd healed him. Her eyes were on the spot where Nnoitra had been before Yuzu used the _Caja_.

His eyes half-closed, bringing her into sharper focus. "Ain't like I can stop you," he replied, shrugging.

Her mouth tilted up—somehow it still didn't look like a smile. Grimmjow knew what real smiles looked like now. This one was more like _his_ than Yuzu's, even if it was small.

"Why was Kurosaki-kun with you?"

He ground his back teeth, pushing a harsh breath out of his lungs. Why the hell was this woman so _nosy_ , anyway? "…I made her a deal," he replied, clicking his tongue against the roof of his mouth. "If she healed Zaraki so we could fight, I'd open her a garganta after."

For the first time in several minutes, she looked directly at him. "You were going to help her escape. Why?"

He crossed his arms, drawing his feet up underneath him. "I don't fuckin' know. I owed her, okay? She ain't… she' doesn't piss me off."

"I see. And your fellow Arrancar… some of them are of the same mind?"

He shrugged. "Yeah, I guess. Starrk likes her—he was just here. Ulquiorra was probably around her the most, but I dunno what the fuck that bastard is thinkin'."

"What of this one?" She nodded to the empty space Nnoitra had been standing in.

Grimmjow's lips peeled back from his teeth. "He's scum and he acts like it." Damn fight-stealing coward. All that shit about weak people not being worth his time, but he sure as hell didn't mind finishing off an injured guy, now did he?

"Good." Unohana's reaction surprised him; he glanced at her sharply. Her smile grew a bit on the left side. "I think I have accumulated enough regrets for one day, you see. I would prefer that this not be another." She moved her attention to the little girl for a second.

"As you seem to understand the concept of reciprocity, Grimmjow-san, I would like to impose upon you for a favor. Please take Yachiru to one of the other groups of shinigami. If you tell them I sent you, they will not attack." She sounded pretty sure about that.

"Yeah? And what do I get for it?"

She tilted her head to the side, smile still in exactly the same place. "I'm sure I'll think of something. For now… consider your life to be an advance."

Something crawled over the surface of his skin. Grimmjow was familiar with the sensation of fear—he'd felt it plenty of times. But it had been a while since he'd really felt it in quite this way. Even with Aizen there was… an understanding. That he had a use, and he'd be alive until he didn't anymore. This woman… Unohana didn't seem to care about things like that. Just what kind of—

He shook his head. It didn't really matter. He was thinking too much; it wasn't like him. "Yeah, all right, fine. But I'm expecting something pretty fucking good."

* * *

It wasn't more than a few minutes after Grimmjow had departed with Yachiru that Retsu sensed the approach of another. This new Arrancar slunk towards the scene like a dog with his tail between his legs, pausing some distance away and moving about in fretful circles. She could almost hear the high-pitched whining.

After what must have been some amount of deliberation, he drew closer to her, zanpakutō drawn. Retsu remained where she was, flicking her eyes to him briefly before returning them to where they were.

"You… you're here to kill Nnoitra-sama," he said, narrowing his visible eye at her.

Retsu pursed her lips. "I am."

From the periphery of her vision, she watched him shift his grip on the blade. "As Nnoitra-sama's _fracción_ , I cannot allow that."

She suppressed a flicker of irritation. "You are incapable of stopping me," she informed him mildly.

He seemed to know that, too—the tip of his zanpakutō wavered in the air. She saw his throat work as he swallowed.

Fortunately, she did not have to wait any longer for the one called Nnoitra to reappear—in an inverse of the process that had pulled him into the punitive dimension, he tore through space and reentered Hueco Mundo directly in front of her eyes.

He was indeed quite tall—Retsu herself had never been a person of considerable height. Comparatively, he towered. She could understand some of Kurosaki-kun's apparent difficulty. However… his size alone did not account for the subtle cues of discomfort Retsu had observed. Nor, indeed, did the fact that he wore a very unpleasant expression. Grimmjow's words had been pertinent— _he's scum, and he acts like it_.

There were many varieties of scum. Nevertheless, Retsu believed she had a good idea of what type this Nnoitra was.

His expression indicated extreme displeasure; particularly when none of his former targets proved to be in sight. He fixed his singular eye on her. Retsu supposed the polite thing to do would be to wait for him to acknowledge her. She didn't feel too much like being polite.

A surge of reiatsu destroyed the camera she knew Kurotsuchi-san had sent along with her. This was not something that should be seen, by the researchers at the Twelfth or anyone else. Retsu rested her hand on Minazuki's hilt, drawing the blade in an unhurried motion. She felt the small ripple of the sword's reiatsu—they were of one mind in this matter.

With a sharp motion, she lodged her sheath in the sand next to her, shifting her grip so that the nodachi was comfortable in her hands.

"Who the fuck are you, woman?" The Espada's upper lip pulled back into a pronounced sneer.

"If you wish to know my name, Arrancar, you will earn it." Retsu shot forward, swinging Minazuki with both hands.

Nnoitra did not attempt to dodge the attack. That was a mistake—a deep slash opened up across his chest. Interesting—that blow had been meant to bisect him. It would seem that natural armor of his was rather impressive.

His face had contorted in shock; she understood why. He'd expected that Minazuki would be turned aside by his hierro. The corner of Retsu's mouth curled; she narrowed her eyes nearly to slits. Her horizontal blow, he did dodge; Nnoitra jumped several meters away, out of her immediate reach. The front of his white uniform sported a blooming patch of red; more spattered to the ground in the wake of his motion. Retsu inhaled; the scent was so familiar. Like coming home again after a long time away.

She shifted stances, bringing both hands up to the level of her shoulder and holding Minazuki parallel to the ground. "I suggest you release your zanpakutō," she advised. "Unless you would prefer to die immediately." She would be quite willing to accommodate such a request, this time.

He snarled at her. "Stupid bitch. You're going to regret giving me the time." Hefting his blade in both hands, Nnoitra glanced down at the cut on his chest, scoffing under his breath. " _Inore, Santa Teresa_!"

A burst of yellow reiatsu accompanied the command; when the flash faded, Retsu observed that Nnoitra had acquired two additional arms. Each of the four grasped the pole of a large scythe. His wound was gone, as though it had healed over in seconds. The remnants of his mask had shifted slightly as well—she supposed it was only reasonable to expect that this and the marked increase in reiatsu pressure were indicative of increased physical attributes.

Perhaps she would have to take him seriously after all.

She stepped into _shunpō_ , swinging Minazuki around for his left side. Avoiding the first attempted block, she ran into the second on the same side. The clang echoed for several seconds—a hairline crack appeared in the scythe where Minazuki had hit. Retsu bent out of the way of the retaliation from the other side; one of the scythes whistled over her head. The other, she simply stopped with her hand.

Rather than disengaging, Nnoitra pushed against her hold. Frowning, Retsu closed her fingers over the blade. It shuddered under her grip—with a series of snaps, it broke off near the middle. _Tsk_ ing, her foe discarded the pole, making a grab for her neck.

His fingers closed over empty air. Retsu flashed away, reappearing behind him and thrusting Minazuki for his back. With surprising alacrity, another two arms grew from his body; he contorted them behind him to block the strike. The attempt was successful—Minazuki pierced both palms, but only scraped the hierro of his back on impact. Wrenching the blade to the side, Retsu sliced one of the new limbs off at the elbow.

Nnoitra jumped away, resetting himself out of her range. Retsu watched the arm grow back with her head tilted to the side. So that's how it was, then. She understood now.

He flexed his new arm. With flashes of yellow light, Nnoitra produced a new scythe in each of his empty hands, bringing him up to six. "You ain't gonna be able to beat me, woman. I'm the strongest Espada, you got that?"

Strongest? What a simple way of looking at the world. Such a superlative had no meaning. At least none that had anything to do with victory.

She might have pitied such a childish mindset. But this man deserved no such sentiment as that. The torment of her subordinate, the death of Kenpachi Zaraki: these were crimes for which he deserved exactly what he was going to receive. Mercy was the artifact of a gentler world than the one Retsu had been forged in.

" _Bakudō #99: Kin_."

Nnoitra attempted to slash at the binding kidō, then to break it with his reiatsu, but the spell was powerful enough that his efforts were futile. All six of his arms were pinned at his sides; driving the iron stakes into the fabric forced him to his knees. He sneered at her from that position, opening his mouth to speak. Likely either to spit invectives at her or else to proclaim the foolishness of attempting to hold him.

Instead of giving him the time, Retsu swung forwards with Minazuki. A single stroke with sharpened reiatsu was enough—Nnoitra's head parted from his body, landing with a gruesome thud in the sand.

He'd protected his internal organs at the expense of his arms. Since he could regenerate the arms, that made complete sense. But it stood to reason that if he could also regenerate his organs, he would not bother exerting so much effort to defend them. Retsu had supposed that this extended to his head and brain as well. As it turned out, even Arrancar could not survive decapitation.

Flicking the blood off Minazuki's blade, she resheathed the zanpakutō. Her eyes landed for a moment on Nnoitra's subordinate. He'd fallen to his knees in the sand; there were no halfhearted attempts to attack her now. She turned from him and left.

There was no longer any reason to stay.

* * *

Kurotsuchi's bankai was every bit as fucking creepy as Renji had expected. More importantly, though…

"Hey, aren't you gonna get her down?"

Kurotsuchi the fukutaichō had been snatched up by one of Szayelaporro's tentacle-things, and even though he was apparently dead now, it was still holding on. Renji'd cut her out of there himself, but he still wasn't in any shape to move, especially not with this poison gas floating around and scratching at his lungs like claws. Really—fake organs, poison, the world's ugliest bankai… his luck was shit, getting backed up by someone like this. He'd have rather dealt with his captain telling him off for not being able to finish things on his own.

At least he was alive.

Before Kurotsuchi could respond, his vice-captain started to cough—the hacking kind like Ukitake got sometimes. Wet and deep the same way. Only this got worse—Renji tipped his head sideways so he could see her. He wished he hadn't as soon as he did.

Her breathing was heavy; she struggled for the air. Each exhale wheezed, making a high-pitched whining kinda noise that sounded a lot like she was trying not to scream, or didn't have enough breath for it but would have been if she did.

"Hey!" he shouted. "Hurry up and get her out of there!" At least _he_ could get loud—she'd fixed his crushed lung before Szayelaporro had grabbed her.

Kurotsuchi didn't seem that concerned, though—he only studied his struggling subordinate like she was something on a piece of glass under one of those microscope things. Renji rolled half-over, searching for Zabimaru—he might be able to help her from here if he could manage the energy for shikai.

From the corner of his eye, he saw the woman's body swell like a balloon blown up way too far. The tentacle around her began to snap, muscle-by-muscle, but it held. Renji cursed under his breath and tried to reach his knees. Where the fuck was his zanpakutō?

"You thought you'd killed me?"

He froze. Impossible.

"I shall tell you the name of Fornicarás's most important power, and the one I take the most pride in. It is called… _Gabriel_."

If Renji's stomach had been anything but squished, he'd probably have lost his lunch on the floor. With a sick squelch, Szayelaporro burst from Kurotsuchi-fukutaichō's mouth, like he'd been there the whole time. Whatever he'd done had left her dried up like a husk, her skin sunken and papery. Renji didn't even know if she was alive or dead—but it looked bad.

"Now then… shall we try this again with introductions? Mayuri Kurotsuchi."

There was a lot more ranting after that—Renji left them to it. Instead of paying attention to it, he pulled himself along by his half-working arms until he was beside the fukutaichō. She was in shitty shape—but he could see that her chest rose and feel ever-so-slightly. She was breathing.

Okay, so… alive for now. From the way her eyes shifted in his general direction, she was conscious, too. But not really that aware; she didn't focus on anything. She had that hazy look, like someone who was really drunk or really tired. Not to mention the fact that she was shriveled like a really, _really_ old person. Renji didn't think that any of the basic first aid he'd picked up would help with this.

But he had to try something. "Hey, Kurotsuchi. Can you hear me?"

Her head turned slightly towards him, but he really couldn't say if that was a response or just gravity.

"Uh… look. Help me out here. What hurts?" She'd injected him with something to re-inflate his lungs, but he didn't know what that was, or if she needed it too, or even if she had any more.

Glancing up, he saw the creepy bankai… explode? He had no idea what the fuck was going on there, but he probably shouldn't expect any help from that asshole.

She blinked, slowly. "In…testines," she managed.

Well, fuck. Internal injuries were way beyond what he could do jack shit about. "You got anything for that I can use?"

"Mayuri-sama…" her head lolled, throwing strands of hair over her face; he wasn't getting anything else out of an unconscious person.

Maybe that meant her captain had something that would treat the injuries? He hoped so—if that was just a call for help in general, it was probably never going to be answered. Renji didn't make a habit of disrespecting the taichō of the Gotei 13, but it seemed like pretty much _everyone_ only barely tolerated Kurotsuchi.

Still… whatever he could say about the guy, he'd clearly done _something_ to Szayelaporro. That was more than Renji had done. In fact, he'd stabbed him clean through the heart, it looked like. The Arrancar fell, then dissolved.

"Hey. Hey, she needs your help over here!"

Kurotsuchi gave him an irritated look. His eyes fell on his fukutaichō—where someone else would have displayed concern or at least pity, Kurotsuchi just curled his lip. Like it was all a huge _inconvenience_.

"Yes, yes—stop yowling. I heard you the first time." From his sash, Kurotsuchi drew out several capped syringes and approached his fukutaichō. Crouching next to her, he jabbed the first one into her left shoulder. The second one went into her thigh muscle, and the longest into her stomach.

Renji didn't understand exactly what part of any of that was helpful, but the results were pretty quick. Kurotsuchi… _rehydrated_ , was the closest word he knew for it. Even that probably wasn't fancy enough for whatever the hell happened, but within a couple of minutes, she looked basically okay again—at least physically.

"Nemu," the captain said, "Dig for the specimen storage."

Her eyebrows pulled together for a second; she glanced at Renji. "Yes, Mayuri-sama," she replied. Like it was the easiest thing in the world, she picked up a slab of stone as big as she was and tossed it away.

"I suppose I should fix you," Kurotsuchi continued, crossing his arms and fixing unblinking eyes on Renji. The way he painted his face made him look like some weird fucking clown—Renji was about as happy to have his help as he was to give it.

But it was necessary, and he guessed they both knew it.

* * *

Rukia fought her way back to her feet with a grunt—Hanatarō had done a good job healing her, but even that couldn't take away the fact that she was exhausted and sore, and probably would be for a while. Byakuya hovered a few feet away; she could tell he wanted to offer assistance, but was concerned he'd offend her if he did.

Maybe he would have, once. She remembered being a lot more concerned about things like that just a few years ago. At this point, though… her pride was pretty much immune to that kind of thing. At least situations like this. Bracing her feet underneath her, Rukia pushed with her hands on her knees until she was standing upright. Pulling in a few breaths, she smiled gratefully at Hanatarō.

"Thanks," she said, rubbing at a sore spot on her shoulder.

"You're welcome," he chirped in reply.

Both of them shifted their eyes to Byakuya, who nodded slightly. Rukia couldn't feel anyone else's reiatsu—they must be too far away. That meant the best chance of finding them was probably just to continue towards the center of the fortress and—

"Can you hear me?"

The voice came from everywhere and inside her head all at once. Rukia recognized it immediately. "Aizen." He must be using _Tenteikūra_ to speak to everyone. From the looks on Byakuya and Hanatarō's faces, they were receiving the broadcast as well.

"Members of the intruding forces," Aizen continued, his tone relaxed and smooth.

Rukia scrunched her nose. That smug little—

"Allow me to first convey my respect. Having felled so many of the Espada is no insignificant feat. More importantly, we will now commence our invasion of the living world. I am afraid, you see, that you have all walked into a trap—a trap other than the one you may have been expecting." He paused. "I wonder, how your under-prepared allies will fare, with seven captains or former captains either dead or trapped here."

Rukia's eyes widened—a short disturbance in the area's reiatsu confirmed that the garganta the reinforcements had entered through were gone. Were they really…?

Byakuya pursed his lips; that was confirmation enough.

"As the numbers have it," Aizen continued, "Soul Society's military strength has been halved. Worse, perhaps. It's quite simple: we will annihilate Karakura Town, create the Ōken, conquer Soul Society, and then crush you at our leisure. Please, enjoy your rest while we are gone." Another pause. "Matsumoto-fukutaichō, I have something of yours. I've left it in the center of Las Noches. Farewell, dear guests."

"…Until we meet again."

* * *

Uryū hit the stone with a massive crash—the wall behind him cracked and split, pieces of it crumbling off and falling to the ground below. He kept himself in the air with _hirenkyaku_ , but only just. The reishi armor over his chest had shattered, protecting his heart but leaving him now with much less between him and the Espada.

He'd been distracted by Aizen's words. Apparently, his Arrancar opponent had not.

"Don't you care that he's leaving you behind?" Curling his hands around the edges of his impact crater, Uryū heaved himself out of it, stepping away when a green lance of energy hurtled towards him. The arrow he fired in retaliation was knocked away with the man's thin, whiplike tail.

The lance destroyed the rest of the wall; the tower teetered forward, crumbling into rubble and throwing up stone dust and sand into the air. Uryū got clear of the cloud, barely twisting out of the way of the next lance. The Arrancar suddenly appeared in front of him; the claws on his hand were poised to spear through the center of his chest.

He blocked with one of Yorugen's blades, holding it in a reverse grip. The scrape of the Espada's claws along the metal set his teeth on edge.

"He was always going to," the Arrancar replied in the same dull voice he used for everything. "It is… good, that he has."

Uryū blinked. "Good? Don't you care that he might be leaving you to die?" Unable to hold the block any longer, he stepped away from it, launching himself above the Espada with a burst of speed.

It was easily matched; the only thing that saved him was that he used _Kage-e_ a second before another lance pierced him from behind. It passed through harmlessly, but before he could switch back, another stabbed into the shoulder of his shadow.

Uryū hissed; the wound appeared on his corporeal shoulder as if he'd been hit there. He felt the same kind of pain, too. Fortunately, he was prepared for it—he hadn't practiced so much with his captain for nothing.

"I see," the Espada said. "You are able make your body incorporeal, but only if your shadow takes the damage in its place."

That was one way to describe it. Uryū pushed away on a reishi current, moving back into his physical body. The Arrancar did not pursue directly; rather, he pointed at Uryū's retreating figure with his index finger. A little ball of black energy coalesced there, the edges indistinct.

" _Cero Oscuras_."

The tiny ball exploded—it was far too fast to dodge. Uryū twisted in midair, bringing Yorugen up for a double slice. At the same time, he flooded his system with all the reishi he'd been passively collecting for the better part of the fight. It pushed into his bloodstream like icewater or liquid nitrogen, a deep chill he could feel in his bones.

The _cero_ hit him with enough force to throw him back over a hundred meters, even with his resistance. Several of the interlocking plates flaked off his reishi armor with a gentle hiss, leaving him only with remnants of it hanging from his belt and over his drawing shoulder. His glasses shattered under the pressure—Uryū closed his eyes against any possible damage. Thankfully, they disintegrated entirely rather than blowing back into his face.

The world was slightly less distinct when he cracked his eyelids; everything he saw had fuzzy edges. He'd lost most of one of his sleeves and all of his cloak; the bare flesh of his arm was smoking faintly. The skin itself was a shade of deep blue, with a faint tracery of whiter lines. Thankfully, it had been strong enough to turn aside what Yorugen hadn't; Uryū had never even imagined a _cero_ this powerful.

Squinting, Uryū decided that the look on the Arrancar's face was actually faint surprise. Clearly, he'd expected that attack to vaporize him—perhaps that was a fair expectation. Letting the _Blut Vene_ recede, he took in a lungful of air. It wasn't something he'd mastered yet—already his body was punishing him for the exertion of pushing it into a heightened state so abruptly.

The Espada scrutinized him for what felt like a long time, though it must have been only a few seconds. Without the cloak, Uryū's reiatsu was no doubt much easier to read; he considered cloaking it with _Kagegaitō_ , but elected not to, for now. While keeping as much information to himself as possible was wise, he needed the reiryoku more. Just in case.

"Do you believe you are strong enough?" The Arrancar asked suddenly.

Uryū's brows knit. "Strong enough for what?"

"To keep her alive."

There was only one _her_ he could possibly be talking about. "That's a strange way to put it. I'm not exactly alone." And it wasn't merely about keeping her alive. It was about bringing her home.

"And yet no one else is here to face me. Perhaps no one else will be there to face Aizen. If none of you alone are stronger than I, your strength as a unit will not be sufficient. And she will die with the rest of you."

Uryū narrowed his eyes. It sounded like… "You… don't want that to happen." It wasn't a sentiment to be mistaken for goodwill in general, but it was a _sentiment_ nevertheless. Leave it to Yuzu to make friends with an Espada.

"No. I will do what is in my power to prevent it. If none among you can even defeat me, then that power is greater than what you have."

"Wouldn't it make more sense just to combine your resources with ours, then? Who says someone has to beat Aizen _by themselves_?" This seemed like a ludicrous reason to stand in the way, but… perhaps there was a certain logic to it. If the person using the logic didn't trust anyone and only cared about one life in the grand scheme of things.

"A hundred ants will no more kill a dragon than one. If all you have are ants, she's better off without you."

"We aren't _ants_ ," Uryū replied, scowling.

"Then you have only to prove it. Allow me to help you understand the naivety of your thinking."

The reiatsu pressure in the air bore down like triple gravity; Uryū had to fight just to keep himself in the air. Black reishi gathered around the the Espada's body, shrouding him entirely. A thin film of sweat broke out nearly spontaneously over Uryū's skin—even from the resurrección, the difference was night and day.

" _Segunda Etapa: Murciélago Calamitoso._ "

The energy burst apart in a heavy shockwave. Uryū was knocked off-balance in the air. Struggling to get his feet back underneath him, he had no time to react to the flash of green light coming in from behind him.

It struck him so hard it nearly snapped his spine in half; Uryū was dragged along its trajectory for several slow, painful seconds, before its momentum tore it free of him. The spear hurtled towards the ground. His hand flew to the new hole in his chest—the lance had gone clean through him just beneath the sternum, between his lungs—somewhere under his heart.

Below, it struck the ground; the explosion reversed his direction, hurling him into the sky above the city—and then _through_ it. Ribs crunched and shattered as he crashed through the stone, out into the darkness above. Blurrily, he could make out two ribbons of blood, one thin and the other thick, trailing from his mouth and his chest.

His vision flickered, then faded to black.

* * *

Suì-Fēng dragged her tongue over her teeth, arms crossed tightly over her torso. She could hear Ōmaeda shifting restlessly besides her. He practically reeked of his fear—sometimes she didn't know why she put up with such a coward. But he had his uses, and like it or not, he was the second-best shinigami in her division.

The truth was, even her body was betraying her; it wracked her with tiny, invisible shudders. She kept a lid on them, of course. No one here would know that _she_ trembled. Slightly ahead of her, the Sōtaichō was rock-steady as usual. It was a testament to the threat Aizen presented that he was taking the field at all. But it was also a matter of confidence for the rest of the Gotei. There was a reason that man had been the only Sōtaichō in two thousand years of history. No one was stronger than him.

And whatever freakish Hollows Aizen had managed to dredge up from the pits of Hueco Mundo weren't going to change a damn thing about that.

Their numbers were relatively thin: aside from herself and her useless vice-captain, there was only the Sōtaichō and Sasakibe, the captains from the Seventh, Eighth, and Thirteenth, and then the fukutaichō from the Third, Fourth, Fifth, and Ninth. Plus those two guys from the Eleventh and the third seat from the Fourth.

"Ōmaeda. Go guard the western pillar." The shuddering sound of his breathing was grating on her nerves.

"But taichō—" He started to protest.

Suì-Fēng glared at him out of the corner of one eye. "Do it. _Now_." He probably wouldn't die if he was just doing that, she figured. "You'll only be in the way up here."

He hid his relief poorly, dipping his head and flashing away. Good. With the Eleventh and Hisagi on the other three, they stood a decent chance of keeping this farce of a construct intact. She returned her attention forward just as the thin black line spread in front of them, gaping open like a disgusting mouth with jagged teeth.

And right out of the vile image stepped the vilest person she could think of: Sōsuke Aizen. Flanked by Tōsen—who was really no better—and a bunch of Arrancar, he casually landed in the air, hands in his pockets. His eyes dragged over the assembled members of the Gotei 13. He didn't even try to hide his amusement, so Suì-Fēng didn't hide her scowl.

She _did_ hide the fact that her tremors moved to her spine. His reiatsu was just… She embraced fear. It was a survival response. Used the right way, it made a person sharper, faster, more reactive. All things that Suì-Fēng needed to be right now. But embracing it was different from showing it. That, her pride would never allow.

A breeze gusted over the empty town. It pulled at her clothes and hair—the metal rings at the ends of her braids clanked together softly. Aizen, Tōsen; no Ichimaru. Maybe one of the others had already gotten him. Four Arrancar that looked like they were in charge. The old guy had a lot behind him; the woman had three. The other two guys were alone. She wasn't sure if that meant they were stronger or weaker than the others. It could be either.

"So what's the plan here?" That was Kira. He'd obviously noticed the absence of his former captain. "Just… go for Aizen?" His eyes moved to Hinamori. Her mouth was set in a firm line; it didn't stop anyone from noticing that her lower lip trembled, or that she _only_ looked at Aizen.

"No," Komamura replied. "Aizen's abilities are unique. In order to be able to concentrate on dealing with him, it would probably be best to deal with those around him first."

Suì-Fēng thought it was stupid that they were only discussing this _now_. Even if they'd only deployed this morning. Still… this was the first time they'd really been able to see what they were up against. She wasn't impressed.

"But… how do we know he won't interfere?" Kira replied.

Suì-Fēng took a step backwards even before the Sōtaichō commanded everyone to move away. The staff around his zanpakutō slowly dissolved—she'd never seen its release in person, but she'd heard enough stories to know she didn't want to be around for that. Aizen made a lazy motion with one hand—Tōsen and all but one of the Espada jumped away from him. Several more of the followers moved even further away—she could sense them heading for the pillars, even with Aizen's massive reiatsu in the way.

No one chased them. That was what the pillar guards were for.

" _Banshō issai kaijin to nase, Ryūjin Jakka._ "

Even as far back as she was, Suì-Fēng felt the heat of the flames that burst from the blade of the sword, surrounding Aizen and the one Arrancar that hadn't moved. All the others were pretty far out of the radius, but since Aizen had been the only target to begin with, it didn't really matter. Excluding the Sōtaichō, that left a captain for every one of the main opponents—that was fine by her.

Komamura moved first, of course—right for Tōsen. People were so predictable when they let their emotions cloud their judgement. Ukitake squared off against the woman, more from proximity than conscious decision, by the look of it. Suì-Fēng herself was closest to the old geezer, so that left Kyōraku to deal with the droopy-eyed loner guy.

Good enough.

* * *

 _Term Dictionary:_

 _Santa Teresa_ – 聖哭螳螂 – The kanji are "Sacred Crying Mantis." In Spanish, _Santa Teresa_ is an idiomatic nickname for the praying mantis. Nnoitra's resurrección. The release command is _inore_ (祈れ), the imperative of "to pray." Its abilities are mostly physical—notably, in this state Nnoitra has extremely strong hierro and high-speed regeneration.

 _Tenteikūra_ – 天挺空羅 – "Heavenly Rickshaws in Silken Air." Bakudō #77. This is the "broadcast" kidō, used to communicate with the chosen targets over a large interval of space. Aizen uses it here as he and his group are leaving Hueco Mundo, because he's a smug bastard and that's how he operates.

 _Blut Vene_ – 静血装 – "Stilled Blood Guise." The German is approximately "blood vein." The defensive form of the Quincy technique _Blut_. Reishi is channeled into the blood stream to fortify the body against attack. It can also be used to stop wounds from bleeding out after they're inflicted. One of a few tricks Uryū picked up from training with his father.

 _Murciélago_ _Calamitoso_ – 黒翼大魔 純粋闇 – "Black-Winged Great Demon, True Despair." Or "Dire Bat," in the Spanish. I'm treating _Segunda Etapa_ as the Arrancar analogue of bankai, including the naming conventions. Since there wasn't really a canon name for this, I just used Ulquiorra's description of it as being like "true despair." And in keeping with the fact that the kanji and the Spanish don't totally match, I kept the literal meaning of the name simpler, but thematic. It's otherwise just as it appears in canon.

 _Ryūjin Jakka_ – 流刃若火 – "Flowing Blade-Like Flame." I can't actually remember if I've done an entry on this one already, so excuse the redundancy if I have. In any case, this is Yamamoto's zanpakutō. It's the most powerful zanpakutō in Soul Society in terms of pure offensive potential. It's also the oldest and strongest fire-type. The release command is _banshō issai kaijin to nase_ (万象一切灰燼と為せ), "reduce all creation to ash." In keeping with a lot of the older zanpakutō in the series, the release is quite long. This sword is a BFD, obviously; enough so that Aizen _made_ an Arrancar with no use other than to counter it.

* * *

Some things I thought about when writing this chapter: Ulquiorra is still learning how to people. Though actually I think his logic is pretty similar to Renji's in TBE/canon Soul Society arc. "She's gonna die, and I don't want that, but I'm going to stop the rescue instead of joining it because the only thing it's doing is providing false hope." Heck, he even has the extra premise "she might have a better chance of surviving if these people are stopped."

Gotta love cringeworthy logic.

Anyway, that's this week's chapter. Happy Labor Day. I think next week's might end up being quite a doozy. We'll see how far I get in ~5k words.


	18. Chapter Eighteen: The Resurgence

_Content Warning:_ Character death; descriptions of blood/gore.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Eighteen: The Resurgence

* * *

Karin pushed off the air, straining her leg muscles and reiryoku both to get herself far enough away from the rapid series of _bala_ potshots Yammy threw at her. Fucking asshole—those _bala_ were just as bad as any _cero_ she'd ever dealt with, and way faster. Even with bankai, she might be…

No. She could do this. She was _going_ to do this. Yuzu was counting on her.

Yammy's tail moved faster than anything that big had a right to—she jumped straight up that time, snapping her tessen shut and using her left hand to help herself over the damn thing. With the extra boost, she cleared it with a vault, landing on the other side unharmed.

A red flash in the corner of her eye was the only warning she got about the incoming _cero_.

"Fuck!"

Karin hugged herself with her reiatsu wings again. The blast caught her square-on, launching her backwards like a ball from a cannon. As soon as she got clear of the cero, she opened the wings again, using them to try and stop her momentum.

That was a mistake. She crashed backwards into a tower; the wings weren't much protection if she wasn't wrapped in them, honestly. Her breath left her in a rush; Karin heard several wet cracks. Bones breaking.

Yammy was pissed—he didn't wait politely for her to crawl out of her crater before he started throwing _bala_ again, right where she'd landed. She knocked the first two out of the way with the flat side of the tessen, but the one after that hit her right in the chest. Pain exploded through her ribcage, rebounding damn near everywhere else as well. Fuck, fuck, _fuck_!

She was dead if she didn't get the hell out of there, right then.

The popping sound of another _bala_ shot being fired reached her, but that meant it was already too late. They traveled faster than—

Her vision turned pink. Or at least, she thought it did. The pain she expected never came, though; instead she heard the sound of the blast hitting close by. In front of her, but all she saw was…

"Karin-chan!" That was Rukia's voice.

It clicked. If that was Rukia, _this_ must be…

"Kuchiki-tai—" The rest of the word was lost in a cough, one of those deep, nasty ones that brought up blood. Each time she tried to breathe, her ribcage speared pain out into the rest of her. White and black dots skittered across her vision. She couldn't hold her bankai anymore; carefully, she let Hisaku go, until she was left holding her shikai. If she tried to keep it going while she was this injured…

The little burst of energy that came from dismissing bankai pitched her forward, and then she was falling. Swearing under her breath, Karin tried to get her feet back under her with _shunpō_ , but she wasn't having much luck. Probably because she had no damn idea which direction _under_ actually was. Fuck, she was dizzy.

"Oh, oh dear—"

She vaguely recognized the owner of the new voice, but there wasn't really a lot of time to care about it. Karin hit the ground, less hard than she expected though. Her vision blacked out for a few seconds—the landing jarred all her injuries and then some—but when she came back to, she realized there was something underneath her.

"Erm, Kurosaki-san." The voice was slightly strained; it took her a second to realize why.

She'd landed _on_ someone. Karin grunted, trying to roll herself off them. Despite the twinging of her wounds, she managed to get to her knees and away from—Yamada?

The person on the ground was definitely him, though—Karin knew most of the officers in Yuzu's division. She had no idea what the hell he was _doing_ here, but it was him. A crash sounded slightly in the distance; only then did she remember the rest of what was going on and think to look for Yammy. It wasn't like she could miss someone that huge.

"It's all right." That was Rukia again. She helped Yamada into a sitting position, then glanced at the massive Espada. "Nii-sama will deal with him. He said you should be looking for Yuzu-chan anyway."

Karin almost snorted before she remembered how much that would probably hurt. Having her captain interfere in her match was a bit of a sting, but Rukia's words soothed it. Yuzu was the important thing here. All the rest of this was just bullshit they had to deal with to get her back. Nodding, Karin tried to stand; it was at that point that her ankle reminded her it was broken. If Rukia hadn't been there to catch her, she'd have toppled back over like a cut tree.

"Ugh," she muttered. "Fuck. Asshole just got stronger the more I pissed him off." She'd been doing pretty well, she thought, but if Yammy had a limit, she hadn't managed to find it. Kuchiki was probably better off strategically to deal with that shit, but still.

Rukia looked at her with obvious concern, but it was Yamada who acted. "Hold still, please, Kurosaki-san. I can at least mend the worst damage before we go."

Karin really wanted to keep moving—she was worried not only about Yuzu, but Uryū as well. She could feel the reiatsu from _that_ fight even here. Uryū's wasn't as strong as she knew it should be. But trying to go in her state would just slow her down in the end, so she relented.

"Sure, Yamada. But don't fix anything you don't have to. I'm not sure how much time we've got."

* * *

The fact that his blackout had been brief was the only reason Uryū was still alive. From the looks of things, however, that might not be the case for much longer. He'd managed to scrape together the reishi to reactivate his _Blut Vene_ ; keeping it going meant he didn't have the resources to use any of his other Quincy abilities, though. He'd shifted from _hirenkyaku_ to _shunpō_ ; without his bow, he had only Yorugen by way of weapons.

The _blut_ was absolutely necessary, however.

The Espada was incredibly fast; he had to push as much reiryoku into each flash step as he could to avoid fatal injury every time his foe threw one of those green lances or slashed at him with his claws. The protection of his blood armor was stopping any of the numerous slashes and stabs he'd sustained from killing him by exsanguination, but it did little for the pain.

Grimly, Uryū took another blow to the shoulder, feeling the Arrancar's claws bite deeply into his skin and scrape along his bone. No blood welled from the wound—but the muscle severed, and his entire arm went slack. He twisted out of the way of the second hit, a stab aimed obviously for his heart.

That hadn't been part of the plan. He needed his arms: both of them. Deciding quickly, he focused, pulling in just a little more reishi than _blut_ demanded. The silver threads of _ransōtengai_ wrapped around the limp limb; preemptively, he wound them around the rest of him as well. They were thin enough to almost be invisible, and required little energy. That might be what saved him.

 _You should not wait much longer._

Yorugen's voice in his head was flavored with concern; slightly tremulous, even. Lucia was much steadier—he could feel her, but she said nothing.

The flash of green light alerted him to the next lance; Uryū swapped places with his shadow. It passed through his physical body, but the danger was not over. Bending, he flowed just enough to the side that it only barely nicked the skin at the juncture of his neck and shoulder. The wound blossomed on the skin of his actual self; though it didn't bleed, he knew it had likely hit something important. This was it.

He had one chance.

 _Believe in me. This will work._

Uryū didn't have much of a choice, but he nodded anyway. Squinting, he picked out the Arrancar's shape in the distance. Shifting his battered body so that one arm pointed forwards, he pushed his reiryoku into the end of Yorugen's left-hand blade. " _Bakudō_ _#42: Midoriami_."

The green net kido shot forward, opening to its full breadth and tangling with the Espada's wings. He couldn't trust it to hold for more than a second, but that was all he needed. Releasing the _Blut Vene,_ he pushed all the reishi back into his bloodstream, but into the parallel system instead. The sudden swap was a shock—it burned like he'd placed his hand on a hot stove, but all over.

All at once, every last one of his wounds started to bleed, and heavily. But the upside to _Blut Arterie_ was that it nearly doubled his current offensive capability—and he was going to need that, against hierro and regeneration this strong. At the same time, he channeled all of his remaining reiryoku into Yorugen's blades. The edges grew indistinct, reiatsu clinging to them like a sticky black fog.

Twisting his whole body, Uryū brought both swords up and over his head, then down in a powerful stroke. " _Kagegyakuten_."

* * *

Rukia cursed the weakness of her body as she ran. The fight with Aaroniero had really taken it out of her—even with Hanatarō's help, she could only move so fast. Karin beside her wasn't exactly in great shape either, but they were managing, for now. Given that it was almost impossible to detect Yuzu's presence at the moment, they'd decided to head to where Uryū was; it wasn't difficult to sense _him._

Whoever he was fighting had a monstrous reiatsu, but he seemed to be holding his own, as far as she could tell. At least he was alive.

Almost as if to prove her wrong, she felt him waver. Rukia grimaced, picking her feet up just a little bit faster. He couldn't die. He just _couldn't._

She'd make sure of it herself, if she had to.

Rukia was so focused on the fight she could feel going on above them that she almost ran smack into someone coming from the other direction. Recognizing the impending collision at the last moment, she veered to the side. Her landing was awkward from her present state of weakness, but she managed to keep her feet at least. It didn't take long to figure out who she'd almost hit.

"Yuzu!" The exclamation was part relief and part joy; Karin threw herself forward at her twin without reservation.

Yuzu looked just as surprised to see them as Rukia was to see her. She wrapped her arms around Karin; her smile only lasted a moment before her eyes moved upwards. Rukia could read her thoughts off her face—there was a great deal of concern there.

The sisters broke apart. They seemed to know without telling each other that any more prolonged reunions would have to wait.

"We've gotta get up there," Karin said.

Yuzu nodded. Her mouth flattened into a thin line. "When we do… we've got to stop the fight."

"What?" Karin blinked with a clear lack of comprehension.

Rukia wasn't sure she understood, either, but there was no time to discuss it. Whatever they were going to do, it had to happen now, and for that, they all had to get up there. Turning to Hanatarō, she tilted her head. "Can you _shunpō_ up there?" She knew the twins were capable, but he was an open question.

He nodded, though. "I can."

"Then let's go."

* * *

Yuzu drew in large gulps of air as they ascended. She could see them now—Uryū and Ulquiorra were fighting. But why? Didn't they know that Aizen had left, that this conflict was pointless now? That it had been pointless all along? Shouldn't… shouldn't they be on the same side in this? Or had she misinterpreted something important?

All four of them drew to a sudden halt when she felt an abrupt shift in Uryū's reiatsu. Yuzu tipped her head up, her eyes rounding. Above them, Uryū swung both of Yorugen's blades forward at once. The blast of reiatsu that resulted cut through the oppressive field of Ulquiorra's spiritual pressure like a hot knife. The visual effect was darkness—just a swath of blackness connecting them, blotting out everything around it.

Ulquiorra, breaking free of what looked like a _midoriami_ , raised his arms to block. Yuzu sucked in a sharp breath; in the second before the darkness enveloped him completely, she saw his limbs start to disintegrate.

"Ishida!" Rukia was the first to move again, launching herself forward in a bounding leap.

Because Uryū was falling; his limp figure hurtling towards the ground. He made no attempt to right himself, no effort to twist or soften the upcoming landing—he just fell like a puppet with cut strings. Dark blood trailed behind him like streamers—too many to count. His reiatsu had all but disappeared.

Karin, Hanatarō, and Yuzu hopped into _shunpō_ behind her, but it was Rukia who got there first, jumping to catch him. She landed on the air; Yuzu pointed at a nearby roof. It looked like they'd been fighting beyond the dome of _Las Noches_ , if the big visible circle of night sky was anything to go by, but he'd fallen far enough that he was back inside.

"Put him down there, Rukia-san!" If his condition was half as bad as Yuzu thought it was, he'd need medical attention immediately. Fortunately, both she and Hanatarō were here.

Rukia nodded; everyone flashed over to the roof in question. Yuzu let her _shunpō_ fade as soon as she felt solid stone underneath her again. While the other three got him laid out and Hanatarō checked his wounds, she released Hasuhime. She wasn't sure how much having her zanpakutō would help; probably straightforward kaidō would be the better solution. But if nothing else, she could help Hanatarō.

Upon closer inspection, Uryū's wounds were awful. Yuzu's heart crept up into her throat; something tightened in her chest. There was a through-and-through wound right below his sternum; it had probably missed his vital organs by fractions of an inch; it might have even nicked his liver, positioned like that. One of his arm muscles was severed down to the bone; countless other slashes and furrows were torn into his flesh.

The worst, though, was the cut on his neck; the way it bled suggested that it had at least scraped by his jugular. He was soaked in his own blood; if he lost much more of it, he would die.

Yuzu set to work, leaving the throat wound to Hanatarō—he was more experienced a healer than she was, and that meant he stood a better chance of repairing it properly. Instead, she turned her attention to the second-worst of the wounds—the hole in his chest. Rukia held one of the sleeves of her shihakushō to the shoulder wound; Yuzu grimaced. Shrugging off her medical pack—she'd grabbed it on her way out, figuring it was better to have than not—she glanced up at Karin.

"There's gauze in there," she said. "Dig it out and let Rukia have it, please." Better to stop the blood flow with something designed for the purpose. Especially when a few more milliliters could make all the difference.

Though the temptation was to heal the wound as fast as possible, even in her panic Yuzu knew that there was a procedure for this. She had to clot the injury first. Switching to that kaidō with both hands, she set to work. Even getting close enough for the kaidō to work meant that her hands were swiftly bloody, too—she ignored the uncomfortable near-panic rattling at the back of her mind. That part of her—the frantic one shouting at her about how this was _Uryū_ and Uryū was practically _family_ and family was _dying_ —would do her absolutely no good here. She was a healer; she had to act like one if she wanted to help him.

Slowly, the bleeding drew to a halt. Yuzu allowed herself a relieved sigh, switching to diagnostics and checking his vitals. "He's stable," she told Hanatarō, who was still bent over the wound in her friend's neck. He nodded slightly, but kept his attention focused on what he was doing. Stable was good, but it wasn't out of the woods. Not by—

"You!" Karin's half-snarled words drew Yuzu's attention up.

There, all his parts miraculously intact, stood Ulquiorra.

He looked… _different_ wasn't really adequate, but it was true. She supposed this must be what his resurrección looked like. His mask had receded until it was only horns on his head, and there were huge, batlike wings extending out to either side. He had claws, too, on both his hands and feet; what looked like ink or ichor stained his front, downwards from the Hollow hole she'd never actually seen before now.

Karin looked _livid_ ; Yuzu could understand that, but more than anything, she was simply confused.

" _Sobiero, Hisaku!_ "

"Karin, don't!"

Yuzu's words drew everyone's attention but Hanatarō's; she herself swapped to a flesh-mending kidō even as she spoke. "Please. Don't attack him."

She could sense it—as impressive as he looked, Ulquiorra's reiatsu was much weaker than usual. He seemed to be ignoring the potential threat presented by her sister in favor of observing her. Yuzu swallowed—she didn't know what he would take from what he saw. Didn't know how he would react, or what he would do. However she thought this was supposed to go, whatever half-formed plans she might have had… this wasn't included.

Karin didn't reseal Hisaku, but she didn't move to attack either. "Why the hell _not_ , Yuzu? He almost killed Uryū!"

She knew. She wished she didn't, but she knew.

Yuzu pulled in a deep breath; it smelled like blood, metallic and sour. Uryū's blood, and probably Ulquiorra's, too. "It doesn't have to be like this," she said softly. She didn't know who she was trying to convince.

Ulquiorra himself seemed to completely ignore everyone who wasn't her. Their eyes met—his sclera were green, and the irises yellow, she noticed. It was uncanny, but also oddly beautiful. Yuzu kept her reiatsu steadily flowing into the kaidō. Fortunately, she could feel what was going on better than she could see it anyway.

For a moment, his gaze dropped to the unconscious Uryū; then lifted back to her. "He won," Ulquiorra asserted, calmly and factually. "It would appear that… I was incorrect."

"…what?" Yuzu glanced down at the rapidly-closing wound on her friend's chest. If anything… it seemed like he must have _lost_. And incorrect about what?

"His last attack," Ulquiorra replied. "My high-speed regeneration has covered the damage, but he destroyed many of my internal organs. I cannot grow them back. Perhaps… perhaps your Gotei 13 will be enough, after all."

Yuzu stiffened. "Your organs?!" she cried. "You… you should have said something sooner! I—" Swiftly, she glanced to the others. Rukia and Karin were watching the byplay with obvious confusion; Karin still stood protectively in front of them.

"Go." That was Hanatarō; he moved his eyes from what he was doing just long enough to glance at her from the corners. "Ishida-san's going to be all right. I can do the rest myself." He smiled, then bobbed his head once. "So go."

Had the circumstances been different, Yuzu would have hugged him right then. Hanatarō understood exactly what she wanted to do without needing to ask, and he didn't try to stop her from doing it. Knowing that Uryū would recover was the tipping point, and he'd just nudged her over the other side. She stood abruptly; the corners of her mouth pulled down when the new view afforded her a better sense of Ulquiorra's condition.

"Yuzu…" Karin let the question hang in the air.

She couldn't pretend she didn't know what it was. Forcing a thin smile, she nodded. "Please Karin… trust me."

Karin's lips pursed, eyes narrowing. Nevertheless, Yuzu saw the exact moment she relented, the line of her shoulders relaxing just fractionally before she sheathed Hisaku.

"Okay. I do."

The center of Yuzu's chest grew warm for just a moment. But then she turned to Ulquiorra, still watching her impassively. She could see it now, though—the weakness his high-speed regeneration had hidden at first. His posture was still straight, but his limbs were too slack; there was a fine sheen of sweat over most of him. She didn't want to imagine what it was taking for him to even remain upright.

But… multiple organs, he'd said—gone. Yuzu knew she _wanted_ to help, but… could she?

Ulquiorra himself didn't seem to believe so. He allowed her to approach without protest, and even sat when she asked him to, but she was reading resignation into his eminent neutrality, and she didn't stop seeing it even when she knelt next to him.

"Which ones are gone?" she asked, too softly for anyone but him to hear.

She _wanted_ to ask what had possessed him to keep something like heavy internal damage from her for so long, but now was not the time for it. Maybe once she'd assessed the damage and actually gotten to work. But not now. Not when every second made a difference.

"Liver, kidneys, stomach, left lung," he replied flatly.

Her breath hitched halfway in—so many. Damage like that… medically, she knew he should not have still been whole. Likely, it was only tremendous power keeping him alive now, and she could feel his reiatsu fading fast.

It meant she had to work even faster.

"Lay back, please," she requested.

There was a heartbeat's worth of pause. She sat suspended, blue-lit hands held in front of her; he was still as marble, eyes pinning her in place.

"I know what I'm asking," Yuzu said. "Please, Ulquiorra."

 _Please let me help you._

He slowly lowered himself to the ground. She breathed out a relieved breath. Mentally chastising herself for feeling relief before her work was actually done, Yuzu leaned Hasuhime up against the front of her shoulder. If she could lift the limit on his high-speed regeneration, she should be able to give him the capacity to regrow his organs, and help with the rest by using her own kaidō. That was a big _if_ , though: who knew how much more it would take to make his regeneration work that way?

Steadying her hands, Yuzu braced them in the air just over Ulquiorra's skin, beneath the uncanny emptiness of his Hollow hole. " _Bensakujo_ ," she whispered.

The light in her hands warped, shifting from pale blue to white; Yuzu pressed down with the reiatsu, letting it slowly bleed into Ulquiorra's skin like water into a sponge. Not enough, and it wouldn't do the job. Too much at once, and he simply wouldn't be able to absorb it. She didn't have so much that she could afford to be wasteful with it even on a good day—it made precision all the more important.

She thought she heard a soft sound, like a sigh, but she couldn't be sure. When he spoke, he gave no indication of the relief such a noise would imply.

"Why are you still…" Ulquiorra's words drew to a stop, as though he did not know how best to finish the question.

That was okay. Yuzu did.

"I told you," she said. "I'm going to be okay, and so are you." She flexed her hands in the air; she was holding them so tensely that they were beginning to shake. She couldn't afford to alter the flow of reiatsu for even a second; his was still tapering away like water from a sieve. He wouldn't be able to keep himself alive with strength of will for much longer.

"I attacked your friend. I meant to kill him." The truth of it was cold, spoken in such a way.

Yuzu knew he did that on purpose. But… in a way, she was glad. Glad he didn't try and deceive her. He never had. "I know," she replied. "And that was wrong. You shouldn't have done it—and I wish you hadn't."

Seeing Uryū in such a state… she'd have one more thing to fuel her nightmares now, for a long time. She couldn't _imagine_ what she'd be feeling right now if he'd died.

But it also brought her pain to see what the fight had done to Ulquiorra—she didn't want him to die any more than Uryū. "But… friends forgive each other, and you're my friend." Hostage situations weren't supposed to make for friends. No doubt there would be many people who thought, if they knew all of this, that she'd been taken in by the hostile circumstances and formed an unhealthy attachment to the few people who hadn't made her fear constantly for her life.

But even so… _even so_.

"Friends," he murmured. His voice was weaker than it should be. "Hearts. What absurd concepts, to apply to something like me. And yet…" The words faded out; his breath shuddered.

Beneath her hands, Yuzu felt Ulquiorra's heart stop.

* * *

"Gin!"

The word, torn from Rangiku's throat, was harsh and raw.

Tōshirō, without a personal connection to the dying man, still felt the pain of that deep in his chest. It hurt her, so it hurt him. Funny how that happened.

She was at his side immediately, hands alight with the first-aid kaidō Tessai had taught her, but anyone who cared to see knew that it wasn't going to be enough. Too little, too late—Ichimaru had already bled out onto the floor enough that it was a minor miracle he was still _conscious._ Still, she tried to heal him, and for whatever reason, Kurosaki-taichō tried to help. If Tōshirō was reading his grim expression right, he knew the same truth—but then he supposed it wasn't in the nature of anyone with that name to give up, no matter the circumstances.

Uncomfortably, Tōshirō crossed his arms over his chest. The interior of this place was massive and empty; they'd come in through the side, he thought, quite a distance from the occasional spike of reiatsu near the front. Part of him thought they should be there, helping; but there was no denying their lingering injuries. Rangiku had done what she was able. Kurosaki-taichō, too. But none of them had near the skills of a Fourth Division officer, and so until they found one of those, they weren't going to be much use to anyone.

Shifting his eyes back to the scene, Tōshirō watched Rangiku accept, slowly, that her oldest friend was really dying. He watched her lift her eyes to their former captain and nod slightly. Watched Kurosaki-taichō return the gesture and back off, giving them some space. Watched her lean down to catch whatever Ichimaru was saying. Her eyes were remarkably dry, at this point.

He supposed that, if he cared to, he could listen. Maybe step a little closer to catch the words. But he had no illusions: whatever words Ichimaru had to say by way of farewell were words only for Rangiku. Tōshirō pressed his lips together when she called him an idiot—not for the words, but for the utter heartbreak in her tone. _Her_ words, Tōshirō could hear just fine.

When Ichimaru was dust and Rangiku stood again, he wasn't sure what he was supposed to say. What he was supposed to do. He'd never understood whatever it was Ichimaru and his fukutaichō shared. He'd never really asked, either. Now, he almost wished he had. So he'd know what to do now that she'd lost it.

That wish was redoubled when Kurosaki-taichō took a step forward and opened his arms. Without even a moment's hesitation, Rangiku stepped into them, wrapping her own around his back and holding on, it seemed, for life itself. Her eyes didn't stay dry.

Tōshirō bit his tongue, paying too much attention to the sting, and to the puddle of red still staining the floor. That would be dust, too, eventually. He swallowed thickly, pointedly keeping his eyes away from the other two. He had no way with people, no instinctive ability or inclination to reach for them.

Not even, it seemed, when he wanted to.

"Kyoka Suigetsu," she said; Tōshirō's attention snapped to her.

Rangiku stepped back from Kurosaki-taichō, wiping at her eyes and sniffling, but visibly collecting herself. She pushed out a breath and straightened her shoulders. "Gi—he said that the way to cancel the illusions of Kyoka Suigetsu is to touch the blade before release."

Tōshirō's eyebrows climbed his forehead. That wouldn't be any good for anyone who'd already seen the thing, but… they had at least a couple of capable shinigami who hadn't.

"That's… good," he said at last, trying to settle on a better word, but unable to come up with one. "Are you—I'm sorry, Matsumoto."

Maybe there _were_ no better words.

Her entire face softened for a moment; she smiled. As someone extremely familiar with all her varieties of mischief and happiness, Tōshirō knew immediately that this expression contained no such levity.

She reached forward, pausing for just a moment a few inches from the top of his head. Tōshirō chose not to step back, and when her hand found his hair and fluffed it, he tolerated the disturbance with minimal scowling.

"Thanks, taichō. I'll be… I'll be okay. We've still got a war to fight, and I don't—" She closed her eyes for a moment. Her fingers curled around the ends of his hair before she took her hand away. When she blinked again, her expression had firmed. "I'm not gonna lose anyone else. Not to Aizen."

"That's the spirit." Kurosaki-taichō nodded solemnly. "Now… I think our first step should be finding some way out of here. What about you, Hitsugaya-taichō?"

Tōshirō tightened his hands over his biceps. "Yes. Since all the garganta we came through have closed, the next logical step is to find a way to open a new one. That probably means tracking down Kurotsuchi. And if we can find Unohana, we should do that, too."

Getting to the fight was one thing. Getting there in good enough shape to make a difference was definitely another.

* * *

 _Term Dictionary:_

 _Bala_ – 虚弾 – The kanji are "Hollow Bullet." The Spanish is just "Bullet." An Arrancar offensive technique, similar in principle to a _cero._ The difference is that _bala_ are weaker, but 20 times faster.

 _Blut Arterie_ – 動血装 – The kanji are "Moving Blood Guise" and the German is simply "Blood Artery." The counterpoint technique to _Blut Vene_ , _Blut Arterie_ drastically increases a Quincy's offensive power by making use of a separate reishi network in the bloodstream. Whereas _Vene_ can slow bloodflow and clot wounds, _Arterie_ actually accelerates bloodflow, which should give you some idea of how ridiculously dangerous it was for Uryū to use it when so severely injured.

 _Kagegyakuten –_ 影逆転 – "Shadow Reversal." Yorugen's most powerful shikai technique, though also the riskiest. As Uryū sustains more damage in battle, this technique passively "charges." At any point he likes, he can choose to release the built-up energy in a blast, which is not blockable by conventional means, as it's delivered by a shadow, which only needs to touch the target to have its effect. It will only work once before the "charge" resets, so balancing the damage he's taken with the damage he needs to do is extremely important. The technique reflects a property of shadows: namely, that they tend to appear darker in the presence of bright light. (Metaphorically, they are strengthened by what they are weak to, something that happens very literally to Uryū when he uses the technique.) All the injuries he takes are retained after use of the technique, making it best suited for use as a finisher.

* * *

Ahem. Bit of a cliffhanger there I guess, with Ulquiorra and all. I'm a little tense myself, even though I already know what's gonna happen. Apologies for the delay; school's been kicking my butt. I have a nice schedule settled now though; hopefully I'll be able to consistently update on Wednesdays from here on out.

P.S.: For anyone wondering what _exactly_ Gin said to Rangiku: that'll be brought up eventually.


	19. Chapter Nineteen: The Renewal

_._

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Nineteen: The Renewal

* * *

The _cero_ burst apart against a nearly-solid wall of tiny blades. Byakuya directed them forward, and they surged towards the Espada like a wave. The artificial light of this place glinted off of each, throwing faint glimmers of soft pink—just enough to make his shikai visible.

Piercing the Arrancar's hierro was proving to be more of a challenge than blocking his thoughtless attacks. Byakuya could easily anticipate his opponent's rage—being so given over to mindless anger made him exceedingly predictable. But his own defenses were every bit as formidable as Byakuya's own. Senbonzakura simply didn't have the ability to cut deeply enough.

Rather than diffuse, he needed his offense to be concentrated.

Fortunately, that was readily available to him as well.

When the blades once again glanced off the giant Arrancar's hide, Byakuya pulled them back in towards himself, reforming the blade of his katana. Perhaps sensing opportunity, the Espada shot several of the smaller, faster energy projectiles at him.

" _Bakudō #39: Enkōsen_." Byakuya raised his free hand, generating the kidō shield in front of it. The red reiatsu spheres crashed against it with enough force to bend his elbow and drive him a step backwards. Frowning slightly, he rotated Senbonzakura's blade until it was point-down, then dropped it.

"Bankai: Senbonzakura Kageyoshi."

The ground rippled beneath his feet; massive sword blades stabbed upwards from beneath the sand, taller even than the Arrancar, caging both of them in. Unsurprisingly, the Espada immediately turned his attention to them, lashing out with a bellow. His fist connected with the blunt side of one of the blades, and it burst apart. Half a second later, the others did as well.

" _Senkei_." The blades gathered together, forming a multitude of katana and surrounding the both of them in four rows. This seemed to either deflate or confound the Arrancar, who seemed unsure of exactly where to direct all of his aggression. Obviously enough, he selected Byakuya himself, who stood with his hands loosely at his sides. Keeping his muscles very intentionally relaxed, he did the work necessary with his mind.

Confident that, when concentrated this way, the blades would be able to get past the Arrancar's hierro, Byakuya elected to end the match as soon as possible. A concession to the fact that his opponent's reiatsu only seemed to increase with time—or perhaps more accurately, with focus. As long as his anger was vague and indistinct, his power was the same.

" _Ikka Senjika._ " As one, all the blades in the _senkei_ formation converged, piercing the Arrancar from all sides. Blood seeped from hundreds of wounds, but remarkably, he remained standing.

Disinclined to see what would happen next, Byakuya instead burst the swords apart again. Now that the Espada's hierro had been broken, there was no need to be concerned about it. Instead, Senbonzakura's tiny razors entered the giant's body through the existing wounds, bursting out elsewhere and making ribbons of his organs in the process.

That, it seemed, was sufficient to kill him; the Arrancar was dust before he finished falling to the sand.

Byakuya sheathed his zanpakutō and started forward. There was yet work to do.

* * *

No.

 _No._

Yuzu braced her hands flat on Ulquiorra's chest, framing the empty space there with spread fingers. Nothing.

It was gone.

His heartbeat was gone.

His breath was still in his lungs.

"No," she said, murmuring it to herself. Or maybe to him, she didn't know.

" _Please_."

But a heart stopping was not the absolute end of a life. In Yuzu's world, no one was dead until they were dust, and Ulquiorra was not yet dust.

She refused to let him be.

He'd been holding himself together with his own reiatsu before. Now that he'd run out, she'd simply have to hold him together with hers. Yuzu reached deep into herself, pulling up everything she had. She could feel heat on her face, and moisture—but those were distant sensations. The way her vision blurred wasn't so distant, but she could ignore it. She could ignore the same cage-rattling panic in the back of her head, shaking at the bars she'd closed it behind, clawing forward for her heart. It threatened to dissolve her into uselessness, into nothing but sadness.

She'd kept it away for more than a month. She'd keep it away a little longer.

Yuzu resisted the urge to simply flood him with healing energy—even now, she had to be careful, had to be precise. Resuscitation wasn't simply a matter of more, more, _more_. She pressed her fingertips into Ulquiorra's chilly skin, reminding herself that he'd felt like that even when he was alive. He wasn't so far gone that he'd lost all heat. He wasn't beyond saving, not yet.

She inhaled, holding the breath in her lungs and focusing on the reiryoku. Pushing it down through her arms, she envisioned it splitting, until each of her fingers was a little conduit. Maybe she imagined the way it trembled and crackled under her skin, maybe she didn't. Either way, she pushed it out in a little burst from each fingertip, directing it all right there, for the heart he claimed he didn't have.

Yuzu didn't care about the metaphor right now. It was enough that he had a real organ in there. It was enough. It would be enough.

There—a tiny stutter, then nothing again. But for a fraction of a second, for _one heartbeat_ , he'd been alive again. She could do this.

 _She_ would be enough.

Carefully measuring out more reiatsu, she repeated the process. This time, he jolted slightly with the force of the kaidō. Nothing. Yuzu bit down hard on her bottom lip; the sting kept her focused, on just the right side of frantic. Again.

Again.

 _Again_.

—There! A flutter under her fingers. She pushed a little more reiatsu in, letting the ebb and flow of her energy match the pace of his heart. It grew stronger, steadier, until it was once again a rhythmic _ba-dump_ , _ba-dump_.

Her arms shook underneath her; Yuzu nearly collapsed halfway on top of him. But her work wasn't done yet. Carefully, she passed a diagnostic over the rest of his torso, trying to figure out what organs were in what states. His lungs were basically functional again, but the rest of them still needed so much work…

"Yu… zu." Ulquiorra had to take a full breath for each flat syllable of her name.

"Shh," she replied. "Don't speak." The energy it would cost him wasn't worth the investment; not when he was still in so much danger.

Though she wouldn't deny that it was a relief to hear even that. So much better than the utter silence before.

His lips parted again, and Yuzu shook her head. "Don't. Don't say anything. If you think I shouldn't be doing this, tell me after it's done. This isn't a negotiation, Ulquiorra." She intentionally echoed his words to her, from the first time they'd met; given the way he looked at her, she knew he recognized them.

Turning from his face, she refocused her attention on repairing his organs. He was going to live.

For now, that was good enough.

* * *

Uryū hadn't been in this much pain in a long time. Possibly ever, if he thought about it.

And yet, it somehow occurred to him that this was a good thing.

That thought took him several moments to parse; he didn't particularly enjoy the sensation of pain, and this much of it was an odd thing to consider good, so—ah.

 _This_ pain meant that he was alive.

Apparently, he must have done something right in his last-ditch effort to defeat the Arrancar who fought him. The one who wanted to keep Yuzu safe. That was another bizarre thought—but it reconciled itself much more easily. It wasn't honestly that difficult to imagine an Arrancar wanting to keep Yuzu safe. She was easy to like. He had no reason to believe that Arrancar were incapable of liking other people.

The logic was actually quite simple up to that point, though it got complicated again afterward.

With great effort, Uryū opened his eyes. He had to shut them again almost immediately against the light, but the second time he tried, he met with more success. Partly because someone's head was blocking the worst of it now. For a few seconds, his vision swam; then it resolved as well as it could without his glasses. Dark hair, a slight smile, obvious relief. Big violet eyes—Rukia, then.

That was odd—he didn't remember her being there. They'd split up, hadn't they? He was glad to see her all the same. Uryū tried to pull his mouth into an expression that matched hers; somehow he was pretty sure he failed.

The soft snort she made all but confirmed it.

"Hey," she said quietly. "You done taking a nap yet? We've got a job to do, you know."

His everything hurt, but he tried to sit up anyway. Her arms supported his back; another pair joined them soon after, and Karin appeared in his vision as well. Her face was streaked with sweat and dirt, but he couldn't imagine that the look on her face meant anything bad.

"We found her, Uryū. Yuzu's… safe." She seemed almost to hesitate on the last word, as though it tasted strangely on her tongue.

Uryū furrowed his brow. Before he could say anything, a loud cracking sound drew his attention. He half-turned his head.

"Oh, sorry." Hanatarō, of all people, was the speaker. "Supplement capsule."

That explained the crunch, but not his presence. At this point, Uryū was quite content to accept the latter; it was likely that he—again—owed Hanatarō a great deal of thanks for his assistance.

Right now, though, there was still something pressing at the back of his thoughts. "Where is she? And what about the others?" He thought he could sense Yuzu now, not too far, but… someone else was there as well?

"Nii-sama is back a ways," Rukia replied, sitting back on her heels once he was obviously able to support himself. "We haven't seen any of the others since we split up. It's hard to feel them either, but…" She trailed off; her mouth pulled to one side in what he read as uncertainty.

"Yuzu's over there." Karin jerked her thumb to her right, which was behind him. "She's… she's trying to heal that Espada you fought, for some reason."

Uryū blinked. That surprised him perhaps least of all. Oddly enough, he wasn't worried about it. Maybe it was simply his fatigue, but… he believed what the Arrancar had said, insofar as he'd bothered to say anything.

Slowly, he shifted his weight forward and then to the side, bringing up his legs and trying to get his feet under the rest of his body. Rukia hovered at his elbow, nearby but not touching him. Karin kept her arms crossed, but didn't step too far away, either. He found he was surprisingly steady. _Exhausted_ , but not in danger of collapse, he didn't think.

"Thank you, Yamada-san."

The medic smiled benignly. "It's no problem, Ishida-san. Yuzu-chan helped, too, actually."

But Uryū could see the signs of exhaustion in Hanatarō as well; obviously healing him had not been an easy endeavor. He'd undertaken it nevertheless. That wasn't as small a thing as Hanatarō appeared to consider it.

Now was hardly the time to insist, however.

" _Your pardon, fellow officers of the Gotei 13. But I suspect now would be a prudent opportunity to reunite. I believe the central staircase to the main building will suffice as a landmark_."

The voice belonged to Captain Unohana, he decided; she must be using _tenteikūra._ Considering that they had Yuzu now—and that Aizen had left—Uryū supposed she was probably right. Luckily the staircase wasn't too far. If he squinted, he could see Yuzu still bent over the Espada, but she sat back on her legs after the message came through, swiping her brow with one forearm.

He couldn't make out her expression—whether the news was good or bad—but he thought it must be good, because a faint shadow of the Arrancar's reiatsu remained. For now… he turned to the others.

"We should go."

* * *

There were two holes in this formation.

Karin's eyes narrowed. Zaraki's absence was the most conspicuous one; it only took one look at Yachiru's exhausted, dirt-streaked face to know what had happened. Unohana confirmed it anyway.

Kurotsuchi was also gone, but he'd at least sent his fukutaichō. She was supporting Renji, who didn't look too hot right now, but was at least alive. Karin felt a little knot in her guts loosen a bit. It disappeared the rest of the way when the old man and his group showed up. Rangiku looked a little shaky, and Hitsugaya was walking a bit weird, but none of them were dead.

Kuchiki-taichō didn't even look ruffled. Then again, she wouldn't put it past him to have made sure of that. He was the type of guy to hide an injury before letting anyone know about it.

The weirdest thing was that the two gaps had almost been filled, in a way. How exactly Yuzu had managed to pick up two Espada allies during her time here was a mystery, but it probably surprised Karin the least out of everyone.

One time, when they were kids, Yuzu had made friends with this mangy, nasty tomcat. One of those that'd as soon scratch you to ribbons as look at you. Karin had stayed well away from the old fleabag—that was just good sense. But Yuzu had fed him and talked to him, and after more than a few bloody welts… that cat had followed her damn near everywhere.

This wasn't that different. Actually, being able to talk to them probably made it easier.

The shorter one with the dark hair—Ulquiorra—kinda shadowed her the same way, actually. Maybe if this had been anything but a warzone where you took what you could get, the suspicious looks would have lasted past the explanation. Or there would have been more questions, or someone would have floated the idea of capture.

But actually… Yuzu's habit of adopting strays was gonna get them all out of here, so everyone was pretty happy to roll with it. Or at least not putting up a fight.

The other one, Grimmjow, kinda prowled around the edges of the discussion—like he couldn't fucking stand still for five seconds. But even he stuck to the same half of the circle Yuzu was on.

"We need to get to the false Karakura Town," Hitsugaya was saying. His arms were crossed and his eyes tracked Grimmjow's movements. "Aizen's already been there for a while—we should be reinforcing the others."

Karin figured he was right about that, except…

Unohana shook her head slightly. "That would be ideal, but most of you are not in the right condition. I can be of assistance, but it will take time, and I will not be able to fully restore everyone right now. You will need to decide how to prioritize—the rest of us can then go back to Soul Society in case things move there."

It went without saying that if Aizen got that far, they were all toast.

"Sure, but… how do we get there? Our gargantas closed, and Kurotsuchi said he can't open 'em again." Renji still stood, one arm slung heavily over Nemu's shoulders. She didn't have any difficulty taking the extra weight, clearly.

Karin tilted her head to the Espada. "They can do it, right? One to Karakura, one to Soul Society?"

Yuzu pursed her lips, glancing between them. "Are you…?"

Ulquiorra nodded. "I can do that much without further recovery," he said flatly.

"Deal's a deal, kid," added Grimmjow. "Better 'n never."

Karin had no idea what he was talking about, but it probably didn't matter.

"All right." Hitsugaya spoke up again, drawing the group's attention. "We need to figure out who's going where, and then get our injuries taken care of. Obviously we need to send in as much power as possible. But… we also need to keep Kyoka Suigetsu in mind."

"Kyoka Suigetsu? Aizen's zanpakutō?" Karin felt her mouth pull to the side. "It makes you see stuff, right?" She didn't get why it needed some kind of special mention. Illusions were annoying, to be sure, but there was usually some way around them.

"They are not ordinary illusions. The power is referred to as 'complete hypnosis,' and to underestimate it would be foolish." Kuchiki spoke up for the first time since they'd all gathered.

Hitsugaya nodded. "Right. But we know the way around it now. You have to touch the blade before Aizen releases shikai. Seeing the release is the trigger—even once, and he's got you. That means most of us are already under it, and anything we see around him could be fake."

Karin raised both eyebrows. "I get it. Me, Yuzu, and Uryū have never seen it, obviously. Is there anyone else?"

Everyone shook their heads, even Yamada.

Well, fuck.

"I think it goes without saying that we have to go, then." That was Uryū.

Karin looked at him and held back a wince. He might be right, but… it wasn't more than half an hour ago that he'd been mostly mincemeat. Even if his parts were all back in working order, he was gonna need more fixing before he could go again. So was she. And Yuzu—

She couldn't think about what kind of condition Yuzu could be in right now. It'd piss her off too much.

"So… us three, the old man, and the captains? Can you heal that many?" She glanced at Unohana and Yamada.

Yuzu's captain nodded serenely. "Yes. Any more and we might take too long; I should return to Soul Society and oversee the triage teams besides. But that many is possible."

Renji and Rukia didn't look particularly happy with the decision, but they didn't openly protest either. Karin hated splitting the group up like this—both of them, as well as Rangiku and Yachiru and Nemu—were damn strong. Maybe strong enough to make a difference. But Renji and Rukia at least were in shitty shape; it'd take a while to get them back up to fighting form, and for all they knew time was almost up already.

"All right. Let's do it, then."

* * *

Yumichika was quite accustomed to pain.

Physical pain was by far the easiest kind to cope with—so the fact that his arm was broken in three places, while indeed painful, was merely an inconvenience in the long run. More annoying right now was the fact that his… _opponent_ had managed to do that much damage in a single attack.

It would appear that his attempts to goad the Arrancar were quite successful; perhaps in excess of what he'd actually been going for. There was recklessness, and then there was this.

Still—he would make it work or die trying. That was, after all, the Eleventh Division way.

His way.

Yumichika's own strike had only managed to slice off a chunk of the Arrancar's hair, making him look frankly even more ridiculous than before. But it might be enough to tip him over the edge into thoughtlessness.

"You troll!" he bellowed. "I won't forgive you for this! _Kirameke, Reina de las Rosas_!"

Yumichika tightened his grip on his zanpakutō. When the dust kicked up by the release cleared, he choked back a disbelieving laugh. That shade of pink was _hideous_. Never mind the impracticality—but perhaps when you had hierro, the protection mere cloth could provide was inconsequential.

Any comment he might have made about the poor sartorial selection of the resurrección, however, was stifled by the immediate need to _move_ —the Arrancar brought his hands together and fired a wide, bright pink _cero_.

Even flash-stepping as fast as he could didn't quite get him out of the radius—Yumichika felt the heat of it across his back as the skin beneath his shihakushō blistered and singed. Pulling in a breath between clenched teeth, he landed on the ground, moving his good arm back, the release command for his zanpakutō on his tongue.

But the Arrancar charged out of the smoke the _cero_ left behind with surprising speed, his hand closing tightly over the fabric at Yumichika's neck. With a sharp jerk, Yumichika felt the ground disappear from underneath his feet—he was hauled a good two or three feet in the air. The material of his collar squeezed uncomfortably against his throat.

"You're finished, shinigami."

Darkness coalesced around them, slowly forming a dome over their heads; Yumichika could see the Arrancar mostly because he was wearing enough white to catch what little light remained. Otherwise, it was hard to tell anything about the environment—or was that just his vision blurring while he choked? It was hard to tell, honestly.

Yumichika felt one of the seams at the back of his turtleneck start to give. There was just enough extra space to pull in a breath. "What… is this?" he forced out. No point in acting until he knew how to win.

The Arrancar smiled slightly—the expression was a cruel one. Yumichika knew the difference very well.

" _Rosa Blanca,_ " he said, voice tinged with pride. "Shrouded in the blackness of these briars, you will be wrapped in white rose petals and die without anyone seeing you."

Without anyone seeing, was it? Well, if he'd been on the fence before, he'd just been given leave to jump right off, hadn't he?

Yumichika smiled. "Thanks," he said. " _Hado #1: Sho._ " He pointed with the index finger of the hand that held his zanpakutō. The kidō wasn't all that strong, but it was enough to force the Arrancar to drop him, and that was all Yumichika needed.

" _Sakikurue, Ruri'iro Kujaku._ " Passing his hand along the air above the blade, Yumichika felt the reiatsu change underneath his palm as the spirit in the sword responded to his preferred name. The eerie green light of the reiatsu vines lit his face from below and spread outwards with the tendrils, casting the dark sphere of the Arrancar's technique into a sickly sort of relief.

The vines snapped outwards with a sharp cracking sound, winding around the Arrancar's limbs and torso, pinning him in place.

"What the hell is this?!" he shouted, struggling against the bonds. Each thrash was less mighty than the last—that was the most insidious part of the whole thing.

Some of the best fighters had to build to their full force. Yumichika's counter for that was simply not to let them.

"It's no use," he said. His eyes flicked to one of the vines, where a bud had sprouted already. "Look."

The bulb rounded, cracking open just slightly at the seams. Yumichika pulled in a breath. At this point, it was really only a matter of waiting patiently for the desired result. Shifting his grip on Ruri'iro Kujaku's tsuka, he straightened. "You see… what's being stored inside those bulbs is your reiatsu. From here on out, any reiatsu you release will belong to the flowers… and when they bloom, your life will end."

* * *

Momo dragged her eyes away from the massive cage of flames keeping Aizen-taichō away from the battle. It was only part of the problem, though—she could feel his reiatsu no matter what he did. Being able to sense other people like that was something she'd always considered comforting rather than frightening, but this was different. This was _him_ , and he felt _different_ now.

More than anything, it reminded her. Of what he'd done. Of what he'd put her and everyone else through. But… especially her.

That was a good thing, maybe. But not if it kept distracting her like this.

"Momo!"

She ducked Sung-Sun's tail in just enough time; the speed with which it passed over her head was an effective reminder of how much it would have hurt if it hit.

These three Arrancar—they'd said they served the one named Harribel. That meant they weren't Espada or anything, but… they were still much stronger than she'd expected. Now wasn't the time to be thinking of anything but this battle.

Building up a fireball on Tobiume's blade, she flung it at Mila Rose with a heave. The lion-like Arrancar dodged it easily enough, but doing so put her right in front of Izuru, who struck with Wabisuke. Only once—she was gone again after, and Appaci fired a _cero_ right for him.

Grimly, Momo swung again. The second fireball careened into the _cero_ ; the impact dispersed both blasts. She pulled in a breath—Momo had never had a _lot_ of reiatsu compared to other fukutaichō—she was seventh-class on a good day. Just flinging raw power around really wasn't the way she worked. But it was hard to stop a _cero_ that strong with finesse.

Izuru flashed to her side; she heard the sound of him pushing a huff out of his nose. He kept looking towards the fire, too—she knew he was concerned more with what he could _not_ sense.

Ichimaru wasn't here, and no one had mentioned it.

There weren't too many things that could mean.

"Try and keep them off me," Izuru said quietly. "If we focus on one of them at a time, we have a better chance."

Momo nodded. It was as good a plan as any. If she could handle the crowd control, Izuru could really hurt them with Wabisuke.

"Sung-Sun has the most reach," she observed. Well, all of them had _ceros_ , but in terms of melee, the Arrancar with the snake-type release was the one to watch out for.

Izuru dipped his chin, then disappeared, flashing away.

Momo grimaced, reaching forward with her free hand, splaying her fingers outwards. " _Bakudō #42: Midoriami_!" The net kidō expanded and shot forward, opening in an attempt to swallow all three of them. " _Carriage of thunder, bridge of a spinning wheel_." She jumped right into the next incantation, pushing more reiatsu down the line of her arm. There was no way the net would catch and hold all three of them.

In fact, Sung-Sun and Mila Rose, on the left and right of Appacci respectively, both got out of the way easily. The net caught on Appacci's antlers, weighing her head down; she struggled to get free of it.

" _With light, divide this into six! Bakudō #61: Rikujōkōrō!_ " She took a step backwards as the second kidō fired; she aimed it for Mila Rose. It hit; Momo flashed forward to grab one of the trailing ends of the kidō net beneath Appacci. When she had it, she crossed under the deerlike Arrancar and charged another fireball along Tobiume's blade.

With a hard toss, she launched the flames; they caught the net on fire on the way up. The fireball itself hit dead-center on Apacci's chest—Momo jumped clear of the smoke. She could hear the rapid clang of metal against something tough—maybe Sung-Sun's scales?

A moment later, the snake Arrancar dropped out of the sky, seemingly weighed down by her own tail. That definitely wasn't the end of things, but at least—

"Was that supposed to hurt?"

Momo's eyes went wide; she threw herself aside in just enough time to avoid being gored on Appacci's antlers. One of the prongs punctured her shihakushō and opened a bloody wound on her ribcage nonetheless. She sucked in a harsh breath, feeling the wound twinge as her chest expanded.

Appacci looked… none the worse for wear. Momo swallowed.

This… this wasn't good at all.

* * *

What an odd sword this Arrancar had.

She'd introduced herself as Tier Harribel—Jūshirō had returned the courtesy, of course. Perhaps in the end such things made little difference; on the other hand, if you had to fight someone, it seemed better to pay the proper respect to them.

But the zanpakutō she carried resembled more cleaver than sword, and it was hollow in the middle. Such a thing seemed unlikely to have much structural integrity, but how easy zanpakutō were to break had more to do with reiatsu than anything. Hers was formidable, all things considered.

Calmly, Jūshirō raised his katana to block, gauging her physical strength as he angled their swords apart. Hers slid easily off the end of his; it lacked the typical heft, but that made it just a fraction faster, he was certain. She brought it back in for a horizontal slash; he blocked again, steady and precise.

He heard a soft scoff from beneath that fearsome mask of hers; Harribel jumped back, resetting herself on the air above the false Karakura Town. Jūshirō didn't mind that—long battles weren't his preference, but they were better than nonstop ones. At least on his lungs. He half-smiled in what he hoped was an amiable sort of way.

"I noticed you haven't used your resurrección," he said mildly, tilting his head to the side. "Is there some reason for that?" Without arrogance, Jūshirō knew that she would need it if she wished to kill him. As for what happened then, well… that would be interesting.

Harribel's bright eyes narrowed. "I do not use what is not yet necessary."

"Ah, I see. I suppose I haven't made myself threatening enough, have I?" He dipped his chin slightly, though he didn't take his eyes off her.

There was a slightly too-long silence. "…You don't seem to want to fight me," she observed.

Jūshirō's smile inched wider. "Well spotted," he confirmed. "In fact, I'd really prefer not to. I think when you get past a certain age, it begins to lose an appeal it might have for the young." Though perhaps Genryūsai-sensei disagreed. But he'd always been more of the exception than the rule when it came to that sort of thing.

"Then go," she said. "I won't follow if you flee."

Jūshirō sighed. If only it were so simple. "I'm afraid I can't do that," he replied. "Even old men will fight, when the stakes are high enough." While he was in no rush from a personal standpoint, it was imperative that as many of them be available to face Aizen as possible.

If what was required to get to the real business before them was a threat… then he'd simply have to become one.

" _Nami kotogotoku waga tate to nare, ikazuchi kotogotoku waga yaiba to nare, Sōgyo no Kotowari._ "

* * *

 _Term Dictionary_ :

 _Ikka Senjika_ – 一咬 千刃花 – "One Bite, Thousand-Bladed Flower." A bankai technique of Byakuya's, useable when Senbonzakura Kageyoshi is in _senkei_ formation. All the blades in the _senkei_ hit a target at once.

 _Reina de las Rosas_ – 宮廷薔薇園ノ美女王 – The kanji are "Beautiful Queen of the Palace Rose Garden," which is a mouthful. The Spanish is "Queen of Roses." Technically in canon it appears without the "las," but… grammar. Charlotte's resurrección. The release command is _kirameke_ (煌めけ), the imperative of "to sparkle/glitter."

 _Ruri'iro Kujaku_ – 瑠璃色孔雀 – "Azure Peacock." Yumchika's zanpakutō. The release command is _sakikurue_ (裂き狂え), the imperative of "to split and deviate." In its proper form, it's a kidō-type weapon that is parasitic on the opponent's reiatsu, wrapping them in vines and draining their energy, which Yumichika can then use to heal himself by consuming the flowers that bloom on the vines. Notably, he often calls his zanpakutō by the wrong name (Fuji Kujaku) and uses it like a melee-type weapon instead.

 _Sōgyo no Kotowari_ – 双魚理 – "Truth of Pisces." Ukitake's zanpakutō. The release command is really freaking long: _nami kotogotoku waga tate to nare, ikazuchi kotogotoku waga yaiba to nare_ (波悉く我が盾となれ雷悉く我が刃となれ), which means roughly "all winds, rise now and become my shield; lightning, strike now and become my sword." The shikai is notable both for having two swords and for being able to redirect energy by absorbing attacks through the left-hand blade and, after adding some of Ukitake's own power, firing from the right. I'll be playing around with some of its properties as well; he fought so infrequently in canon that we don't even know what his bankai was.

* * *

So, Yuzu managed to save Ulquiorra. I definitely considered killing him; it would have been appropriately feely and tragic, I suppose. But I elected not to for a couple reasons: one, I think there's still some meaningful character development to be done with him. Two, the way this was done in canon was like… _pointlessly_ tragic. The person with reality-bending healing powers and an acknowledged tendency to heal literally anyone, friend or enemy, seems to spontaneously forget how to do that while he's talking about his organs being gone. Yuzu is very good at healing. Yuzu is also actually Ulquiorra's friend. Ergo… she wasn't going to stand there and wait for him to become a pile of dirt.

Other stuff: the exact timing of things got a little thrown off by my inclination to finish off Hueco Mundo stuff before seriously tackling the Fake Karakura stuff. So… it might be a while before the cavalry shows up here in FKT. Most of the scenes here are, of course, happening at the same time.

I've given up on trying to estimate how many more chapters are left in this fic. It always seems to be more than I think it is.

* * *

Thanks for the reviews, everyone. They're super encouraging; even the ones I have to run through a translator. :)


	20. Chapter Twenty: Bad to Worse

.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Twenty: Bad to Worse

* * *

Suì-Fēng flexed her hand. The muscles responded just as well to the mental command as they always had—strong and controlled. So why was it that every time she tried to hit her opponent, she was suddenly so slow and weak? She ground her molars together; she hated the sound it made, but it was a tiny outlet for the frustration she couldn't show any other way.

She wasn't stupid—everyone needed to keep their strength and their wits about them if they wanted to take down these damn Arrancar and the filthy traitor scum that commanded them. Pushing a hard breath out of her nose, she narrowed her eyes at the old man standing across from her.

He'd sat himself down on a chair before, like a fat vulture on his perch. But he'd sent off all the carrion flies that followed after him, and she'd forced him to at least _stand_ to fight her. That wasn't much of an accomplishment, but for exactly that reason she couldn't even _tolerate_ the thought of being so weak that she couldn't manage it.

She still had yet to hit him with anything powerful enough to do damage, and she had no idea _why_.

Parting her lips to suck a breath in between her teeth, Suì-Fēng held it in her lungs for half a second before she stepped into _shunpō_. She was faster than this Baraggan Louisenbairn. She _knew_ it. Whatever thing he was doing to make her hits weak wouldn't work if she built to the right speed beforehand.

Suì-Fēng veered to the left, striking out with her right arm. But there it was—that strange, slow drag she couldn't explain. Like suddenly she was trying to move through water, only even the extra force she'd put behind the blow didn't make a difference. It wasn't an external resistance, then.

She jumped away before he could retaliate. If he wasn't thickening the air around himself or applying reiatsu pressure or whatever else… he had to be doing something to _her._ But _what_?

"Can't figure it out?" The old man raised the brow over his unscarred eye, completely unconcerned. "You're wondering about what kind of ability I have and are unable to make a clear distinction, right?"

Suì-Fēng pressed her lips together; they pulled into a scowl. She had a feeling this was going to be a long-winded explanation. Old men were always like that when they spoke to her. Like she was a little girl instead of a captain of the Gotei 13.

"Each Espada," he said, meeting her eyes directly. "Has an aspect of death that they rule over. These forms are the eleven main causes of death amongst humans. They are also each Espada's abilities, ideology, and reason for existence. Rage, greed, madness, intoxication, destruction, despair, emptiness, sacrifice, isolation, and predation are the others." He tilted his chin up, looking down his crooked nose at her.

"And the aspect of death that _I_ rule over is old age. Time. The mightiest and most absolute power of death. It stands in the way of _every_ living being."

Suì-Fēng sucked in a breath—he'd disappeared. No sooner had the thought occurred to her than he was right beside her, reaching out and laying his hand on her left shoulder.

"If I merely touch you and exercise my will like so… I can immerse just your bones in old age." He removed his hand.

Her eyes rounded; this was—

The sound of her arm breaking wasn't the wet snap she knew. It was… crumbling. Like something weak falling apart slowly, grinding against itself and becoming pieces. But the something was her _arm_.

"This can't—!"

"You cannot comprehend it," he rumbled, shaking his head just once. "That is the way of death."

Suì-Fēng whirled to face him, bracing her weak arm with her other hand. Baraggan brandished a massive, double-bladed axe in one hand now; he'd retrieved it from over his back.

"And, from here on, not a single thing will happen that you will be able to understand." He shifted his grip on the haft of the axe; sunlight glinted off one of the broad edges.

" _Kuchiro, Arrogante._ "

* * *

"Can't we just pretend to fight long enough for everyone else to finish? I'm not really interested in crossing swords with you." Coyote blinked slowly at the eccentrically-dressed shinigami who'd stepped forward to face off with him. He kept his hands in his pockets.

 _You think he'll just go for that?_

Lilynette didn't seem to think it was all that likely. Maybe it wasn't. But there was only one way to find out.

"I'd like it better that way too," the shinigami said with a sagacious nod. There seemed to be something less-than-genuine about it, though. "Pain is so unpleasant." He sighed, reaching up and tipping his hat back with one hand. "But you know… this time around… we really can't do that."

 _I told you so._

Slowly removing one hand, Coyote brought it up to his face and scrubbed at his cheek. A sigh sat deep in his lungs, but he didn't let it out yet.

"No," he said heavily. "I mean… I really can't fight you." The sigh—no longer containable—rushed out softly. "I'm not gonna break her heart like that, even if…"

Even if the shinigami insisted. It was a pretty strange position to be in. Coyote couldn't raise arms against her friends and comrades, the people she cared about. After all… he understood what that was like now—to care about people as friends and comrades. To really have such relationships. Or at least one of them. If he thought about it hard enough, he could imagine how much he'd hate it if someone hurt her. Preventing that was the _point_ of so much of what he'd done in the last few days.

He wasn't going to put her through that pain. Not if he could prevent it.

The shinigami regarded him with sharp eyes. They were dark—not just in the color, but the look they had to them. Whoever this guy was, he'd seen just as many terrible things as Coyote had. Maybe more.

Her eyes weren't like that at all. He didn't want to be the reason they changed.

"Is that so?" the shinigami asked. It seemed mostly rhetorical, something he confirmed by continuing to talk. "Breaking a woman's heart is serious business. I certainly wouldn't want to do it, so I believe I can understand your position. I have to ask though… exactly which _her_ are we talking about here?" From the sly edge to his tone, Coyote supposed he already had a guess.

Well, it wasn't any skin off his teeth to confirm it. "Yuzu Kurosaki," he said. For a moment, he dared to take his eyes off the shinigami to glance at the too-bright conflagration of flames caging Aizen and Anzparrejar. The fire wouldn't last forever; he could be sure of that. But for now…

"Aizen lost the rest of his leverage over me when he got trapped by that," he continued bluntly. "But that doesn't mean he'll never get it back. Assuming he doesn't just kill me for this."

The shinigami folded his hands into his sleeves, glancing in the same direction for a few seconds before returning his eyes to Coyote. "Let's start again," he suggested, a half-smile turning his mouth up at the corner. "I'm Shunsui Kyōraku, Captain of the Eighth Division. And you are?"

He blinked slowly. "Coyote Starrk. Primera Espada."

If anything, the mention of his rank increased the breadth of Kyōraku's smile. "Interesting. So, Coyote-san. Let me see if I have this right: you, at some point or another, decided that you don't want to hurt Yuzu-chan, or do anything that would break her heart. But you're here, because of course Sōsuke-san would have been able to see that. Now that he's… out of the fight for a bit, you're looking for some way out of this that doesn't involve killing any of us or dying. Am I on the right track here?"

Coyote nodded. It was a fair way of putting it, if missing a few of the details.

Kyōraku did that fake sage head-bob again, eyes narrow and sharp.

"In that case, I think I have an idea."

* * *

"Have you truly fallen so far, Kaname?!" Sajin couldn't believe what was sanding before him.

Kaname, his friend—wearing the mask of a Hollow.

It was a featureless white, with only one black vertical line splitting it down the middle. But of course Kaname had never needed his eyes. He wouldn't need them now, either. Sajin clenched his fists, feeling his claws bite into his palms even blunted by his gloves. His heart constricted in his chest.

If he was this far gone… was there truly any bringing him back? He had embraced the power of a Hollow, power not earned but given by that damn Aizen. What could Sajin say or do to overcome something like _that_?

No.

There had to be a way. There was always a way. Kaname was his friend—had _been_ his friend for a long time. That meant something. It didn't stop meaning something because of this. Five years… five years _could not_ destroy a century of companionship and loyalty.

"Why?" he demanded. "Why have you strayed onto this path, Kaname? You had enough power as a shinigami. Why have you embraced this corruption?"

"Corruption?" Kaname echoed the word like it tasted strangely to him. "Why is moving away from shinigami and closer to Hollow considered corruption? Such words can only come from a narrow-minded, two-dimensional argument that separates shinigami and Hollows into good and evil."

"No!" Sajin snarled, tightening his grip on Tenken. "The corruption I speak of is betraying your friends, allies, and even subordinates in an attempt to gain excessive power!"

"Why?" Kaname replied. "Because I am afraid. For one hundred years… my fear has been being assimilated by you shinigami and dying."

"For one hundred…" Sajin nearly choked on the words. "All this time, you've been…?"

Kaname tipped his head to the side. "Isn't that obvious by now? I have been Aizen-sama's loyal subordinate from the beginning. The person you believed you knew was only an illusion you wanted to believe. If you had really known how to look, you would have been able to see the truth."

The whole… Sajin had known that Kaname would have had to have joined with Aizen in advance of the events of five years ago. But to learn that it had been so long—that nearly their entire acquaintance had been tainted with this…

What was left was far less to believe in. But—

 _But._

It was still something.

" _Bankai:_ _Kokujō Tengen Myō'ō_!" Sajin manifested the enormous suit of armor behind him and swung. It echoed his motions, the massive sword it carried creating a vacuum in the air with the speed it raced for Kaname.

If Kaname could not be talked back to the person he'd been, then… Sajin would simply have to find another solution.

Kaname avoided the swing with apparent ease; whatever else the Hollowfication had done, it had granted him greater speed than Sajin remembered him having. Gritting his teeth together, he curled his lips up in a silent snarl, flashing forward for a follow-up.

" _Suzumushi Hyakushiki: Grillar Grillo._ " Kaname was enveloped in a burst of darkness before Sajin could reach him.

When it cleared away, he pulled in a hard breath. His friend was completely covered in dark fur, four elongated arms tipped with strange claws connected to his torso. But what was truly alarming was the fact that his chest now bore a Hollow hole, proof that this was a Hollow's power in truth. It was undeniable.

"Kaname…" Sajin gritted his teeth. Words alone would not bring his friend back. So be it.

He swung.

* * *

Shinji un-bent his knee, stretching it forward until his leg was laying flat on the ground in front of him. He kept his arms crossed over his chest, only half-observing the training match going on down in the ring. Next to him, Hachi kept up an extra barrier—Hiyori wanted to practice with her mask on, so it was better safe than sorry.

"I take it the switch went all right, then?" Shinji asked, leaning his head far enough to one side to stretch the muscles in his neck. He did the same thing on the other side.

Hachi nodded. "Yes. All of the humans in this town are now asleep, and we've been moved to the outer edges of Soul Society. Urahara-san says he will open a Senkaimon for us whenever we want to leave."

"Oh yeah?" Shinji curled his lips back from his teeth, baring them for a second. "That guy… I swear."

He thought he could predict them. Know what they were going to do before they did it. Know what they wanted before they decided. The funny part was… he usually did. Shinji dealt with that by reminding himself that once, Kisuke had been a derpy little dipshit who needed a helluva lot of kicking in the pants before he got his shit together.

It made him feel like he had a hand in whatever the fuck that guy was now. Some kinda strategic genius or somethin'. Whatever. The important part was, he was gonna get them where they wanted to go. If he was using them along the way, well… that was fine. They were using him, too. They had been for a long time, and he hadn't complained. Shinji figured they could return the favor.

The _other_ favor wasn't something you could just give back, so the little one would have to do.

In the ring, Hiyori shrieked, charging Rose with that stupid-big cleaver of hers. Rose, of course, slid away from the blow like water, bringing his whip around in retaliation. It caught in one of the gaps between the serrated edges of Hiyori's zanpakutō; Rose yanked back, pitching her forward into a raised knee.

Her mask cracked and flaked away; Shinji snorted under his breath at the string of cusswords that followed. She took everything so damn personally—every loss, every wound… every betrayal. And she held a grudge even better than he did, which was saying something, considering.

"Hey, quit beatin' each other up and come get dinner!" Kensei appeared at the top of the stairs, decked out in that ridiculous pink apron.

Love and Lisa, lounging in another corner of the training area—probably reading that damn manga again—turned their heads at this. When Mashiro poked her head around Kensei's elbow to contribute, Shinji nipped the conversation in the bud.

"Nuh-uh. We don't have the time fer that. Battle with Aizen's probably already started; we've gotta get to that fake replica town pronto."

Kensei scowled at him. "If you knew we were gonna do that, why the fuck did you let me make all this food?"

Shinji shrugged. "Didn't want anyone getting antsy before it was time to go. Now c'mon. Get yer stuff, everyone. We've got some debts ta pay."

* * *

Izuru's eyes darted between the three Arrancar. Between them, he and Momo had forced the fight to ground level, but even slowed by the weight of whatever he'd managed to hit with Wabisuke, the three of them were dangerously quick. He could tell Momo was just about out of reiatsu. He was doing a little better, since he hadn't needed to use a lot of kidō yet and wasn't as badly injured, but…

That wasn't especially good news anyway.

"That's it!" Mila Rose shouted, baring her teeth at them in a snarl. It befitted her leonine aspect, he supposed. "Come on you guys, this is pointless. Let's just use it!"

"I fucking hate using it; you know that!" Apacci was apparently not in favor of whatever new development this might be.

Izuru glanced sideways at Momo. She was half-bent, trying to catch her breath. If they argued about whatever this was for long enough, the two of them might be able to think up a different strategy. Perhaps now that they were at least somewhat slower, he could get behind one of them and—

"If you two would stop arguing like the barbarians you are and actually think for a change, you would know that we shouldn't leave our shinigami friends waiting." Snobbish as she was, Sung-Sun was more aware than the other two of the danger of leaving two intelligent opponents with free time.

That was unfortunate.

"Fine," Apacci said, the word trailing into a growl of frustration. "I'll do it."

Unsure exactly what _it_ was, Izuru tensed. He brought Wabisuke before him in a two-handed grip. Next to him, Momo forced herself to straighten, glancing only once at the flaming spot in the sky high above them.

"Are you okay?" he asked her, not removing his attention from the three Arrancar.

"Yes," she replied. Her voice wasn't as strong as she probably wanted it to be; Izuru knew that wound had to be bothering her.

He could smell the blood even from where he was. But he trusted her to know what her limits were—they weren't the kind of people who pushed too far past their capabilities. Historically, they'd left that to Renji. At just this moment, Izuru was hoping it might have rubbed off on them, at least a bit, because they were probably going to need it.

More or less in synch, the three Arrancar gripped their left arms with their right ones. It didn't occur to him what they were doing until they'd actually torn the limbs from their stumps, all the way up to the shoulder socket-joints. Each arm disappeared in a flash of light.

"What the…?" If Izuru had to guess, that must be…

"Sacrificial kidō?" Momo apparently thought the same.

The three lights converged in front of the Arrancar, merging and expanding until there was a wall of color nearly three stories tall. Slowly, it pinched in at the edges, assuming a roughly-humanoid shape. By the time it solidified, Izuru had a better idea of what it was supposed to be—if there was really a _kind_ of thing that this creature was.

It was bipedal, though the feet were massive hooves, attached to fur-covered legs not entirely unlike Apacci's. Its torso was basically humanesque; it had arms resembling Mila Rose's, and a mane of hair to match. Its head was covered by a deer-shaped mask with antlers, but its tail was scaled and snakelike.

Not more than a second after the creature fully solidified, it struck—faster than Izuru would have expected for something so big.

" _Bakudo_ —" Momo's kidō was nowhere near fast enough, and the creature tore a chunk out of her body when she didn't quite manage to dodge, either.

Izuru pulled in a sharp breath—that was a lot of blood.

Even a moment of inattention would make his fate just the same.

Pushing himself back into the air, Izuru moved left. Hopefully it would follow him and not take anything else out of Momo. He could see her blood dripping from between its closed fingers, still. If he hadn't been able to detect just a flicker of her reiatsu, he'd have thought her dead. But any attempt to heal her would kill them both, with no one to occupy this… thing.

Muttering the incantation for _tenteikūra_ , Izuru turned, facing the gigantic being warily. Still weighed down, its creators spoke to him from the ground. "Do be careful," Apacci said, obvious sarcasm lacing the words. "Ayon is _dreadfully_ strong. Wouldn't want to end up like your little friend, right?"

"Kotetsu-fukutaichō," Izuru spoke low and urgent into the communication kidō manifested in his hands. "Momo is injured—badly. If there's any way you can get to her, please… please do. It's dangerous down here, but I'm—"

He clamped his mouth shut and dodged another furious swipe, abandoning the kidō to focus on the fight. Even then, it was a near miss; Izuru found himself glancing down at a new tear in his shihakushō. Gritting his teeth, he firmed his grip on Wabisuke in one hand and pushed reiatsu down his other arm.

If he could last long enough, someone else's fight might finish soon enough for them to reinforce him.

Battle was a grim thing, indeed.

* * *

Genryūsai stood alone in the middle of the battlefield, his eyes narrowed to slits but his attention cast in all directions. Reading the reiatsu in the area was as good a way to understand the flow of battle as to see it. Perhaps better, if one knew what to seek.

At each of the four cardinal directions, he felt the battles before the pillars anchoring this false location to the living world. He knew that three of the fighters he had deployed there had done their jobs. One had not—the fool believed that hiding his bankai was worth his death. As if bankai alone made a captain.

He should know by now that anyone who would willingly suffer a defeat for the sake of pride had no place being a captain anyway.

Fortunately, this had been accounted for well enough. Retsu's third seat knew what to do if one of the pillars fell, as it seemed would happen.

The remaining fukutaichō on the field were making a poor showing for themselves against that unthinking beast—he would likely be required to intercede on their behalf momentarily. Killing such a thing was not something he would find any satisfaction in; nevertheless it was clear that it must be done.

The taichō were meeting mixed results as well; Suì-Fēng's relative youth and inexperience in such matters were becoming clear. Perhaps asking the leader of the Ōnmitsukidō to participate in open-field combat was less than sound, in terms of tactics. But there had been—and was—no choice. Jūshirō was not overly troubled by his foe; unfortunately such a state of affairs was only guaranteed to hold for as long as his lungs did.

Genryūsai had always found it blatantly unfair that such an otherwise formidable and worthy student should be hobbled in such a way, while utterly useless and craven people enjoyed health as though it were a right and not a matter of luck. But he'd known the world was unfair long before he'd ever met Jūshirō. Unfair it would remain.

Sajin struggled. To come to grips with the fact that his longtime friend was indeed a cowardly traitor and then also to do anything about it. Another place he might be forced to intercede.

Shunsui and his foe both had masked their reiatsu and disappeared from the field. Whatever that boy was up to would likely be of benefit in the end—Genryūsai had to acknowledge that. Shunsui was no scientist, nor spy, nor even really an intellectual in the usual sense. He knew what conventional strategy demanded, which tactics were tried and true… and most often laughed in the face of such things. Because he understood people, well enough to see each one as an individual and tailor his decisions to that knowledge.

For a long time, Genryūsai had undervalued that. He hoped he had not seen its merits too late.

Chōjirō maintained the barrier around the town steadily—none of the Arrancar had moved that far out, it seemed.

The question now wasn't whether he _should_ act, but in what capacity. Without knowledge of what Shunsui intended, he could not factor that into his decision, and there were several obvious demands for his attention. Suì-Fēng, Kira and Hinamori, and Sajin were all in immediate danger, and without ready reinforcement.

Deciding that the taichō could hold out longer, Genryūsai had no sooner stepped into _shunpō_ than he brought himself up short. The reiatsu field had shifted—a garganta was opening.

It appeared in the air close to the place he'd trapped Aizen with Ryūjin Jakka's flames. From Genryūsai's angle, it was slightly above and to the left of the enclosure he'd made with his fire. The line in space became a yawning chasm, and out stepped a small, childlike figure.

He felt his mouth pull down into a frown. There had been something about this boy in Hitsugaya's reports. This Arrancar had been able to swallow a level 99 Hadō, delivered by a former Grand Kidō Chief, and sustain no damage whatsoever. Such a thing… even he would not have been left unhurt if he simply took such a blow head-on. What exactly this capability amounted to was much less clear—though both Yoruichi Shihōin and Tessai Tsukabishi had fought this child, all they had been able to infer was that it was some kind of reiatsu absorption.

If it was so encompassing as to be able to consume such a mighty kidō, then Genryūsai knew what he was required to do in this battle.

The boy's vacant expression cleared for a moment; Ryūjin Jakka's flames drew his attention, and like a moth he gravitated towards them. Genryūsai's hands tightened on his zanpakutō's tsuka. The child screamed—inchoate and piercing—and when all his breath was expelled, he drew it back in again.

Genryūsai had never seen anything like it. With the Arrancar's breath went Ryūjin Jakka's flames, pulled towards the boy like they were being sucked into a vacuum or void. They parted like a curtain, and by the time the child closed his teeth over the last of them, Aizen and that other Espada were standing unimpeded before him.

Obviously correctly interpreting the expression on Genryūsai's face, Aizen smiled subtly. His eyes narrowed with mirth—this was all a game to that foolish traitor, and it was a game he believed himself to have already won. That much was clear. But his confidence had come far too early, if these were the troops he had mustered. The Gotei 13 were holding their own, as they should.

Someone as intelligent as Aizen would understand that at a glance. Which meant his confidence issued from somewhere else. Something that had not yet been deployed. The child?

Genryūsai's eyes shifted to the boy. He didn't seem to be looking at anything in particular; a line of drool trailed from the corner of his mouth down his chin. The reports describing an utter lack of rational faculty were in no measure exaggerated, it seemed. Such a creature could not be the lynchpin of the plan. And the Arrancar the Hōgyoku had made were either here or presumably in Hueco Mundo. So… what made the difference? What gave him such assurance?

"Good afternoon, Sōtaichō," Aizen said mildly. "I had _thought_ you might take the field."

"It would not have been necessary, but for your foolishness," Genryūsai chided, missing the presence of a solid floor to strike his staff against. "To believe you could create an Ōken and enter the Soul King's palace. Such arrogance."

"Arrogance?" Aizen feigned consideration for a moment. "I suppose it does seem that way, from your limited perspective." He turned to the masked subordinate beside him. "Do as you will."

The Arrancar nodded once, then flashed away. Genryūsai did not give chase, for the moment. Instead, he shifted his grip on his zanpakutō. Whatever it was that Aizen believed he was hiding that ensured his victory, the surest way of being able to counter it was to flush it out first. He had not won so many battles without understanding the value of information.

Slowly, he pushed reiatsu into the blade of his sword. "What else could it be?" he asked, voice heavy. "Do you truly think that, with your level of power, you can cut me down?"

Aizen raised both eyebrows. "I think nothing of the sort," he replied slyly. "For in fact, I have already done so."

"Be silent!" Genryūsai thundered, stepping into shunpō and swinging Ryūjin Jakka. He was seconds from releasing a _Taimatsu_ attack when he felt Kyōka Suigetsu puncture his stomach. Shifting at the last second so the sword skidded past anything vital, he caught Aizen's forearm in a strong grip, wrapping his fingers most of the way around the limb and holding it firmly in place.

"I've got you, Sōsuke Aizen."

The traitor paused a moment, tilting his head almost curiously. "…How amusing," he murmured. "And what are you going to do now? Are you sure that the arm you've grabbed is really my arm?"

"That would be an issue, if I were merely using my eyes to see or my skin to feel," Genryūsai agreed. "But it is impossible for me to misread the reiatsu of the zanpakutō lodged in my stomach." He pulled in a harsh breath, pointing Ryūjin Jakka directly downwards.

" _Ennetsu Jigoku._ " Seven towering pillars of flame erupted from the ground, surrounding the field.

"While you were trapped behind my fire and your subordinates were preoccupied with mine, I did not merely stand idle," Genryūsai said. "You and I will die here, in this burning Hell."

"And what about your subordinates? As it stands, they too will be caught up in this _Ennetsu Jigoku_ of yours…"

Genryūsai snorted. The height of hypocrisy, to lecture _him_ about concern for one's subordinates. "They are prepared for that," he said. "Dying to exterminate a great evil… this is the very spirit of the Gotei 13."

"I see." Aizen seemed entirely unconcerned—it was enough that Genryūsai hesitated for just a moment before closing in on the replica town with the pillars of flame.

"Aaaaaaaa."

It couldn't be.

A hand closed over Ryūjin Jakka's blade; the flames vanished with a puff of smoke. In all directions, the pillars dissipated in exactly the same way, leaving no trace of themselves behind. Even the temperature reverted, as if he had never initiated the technique at all.

How? How was such a thing possible? Though Genryūsai had once known a force that could withstand the fire, never had anything simply _dispersed_ it.

"Shall I enlighten you?" Aizen's polite tone was a jarring contrast to the urgency of Genryūsai's thoughts. "It is true that your Ryūjin Jakka is the most powerful zanpakutō in existence. That goes without saying. If we were to fight directly, your combat ability might exceed even my own. However… if one were to abandon all other abilities, and specialize in only one thing, then they would be able to oppose even such incredible power."

Aizen's eyes shifted so that he was looking at the Arrancar over Genryūsai's shoulder. He didn't need to turn around to read the child's reiatsu.

"Wonderweiss is the only modified Arrancar. He was created for the sole purpose of suppressing fire as powerful as that generated by your Ryūjin Jakka. For this single ability, Wonderwiess lost language, knowledge, his memory, and even reason itself. But what he gained was a resurrección with a very specific nature."

The traitor's eyes narrowed. "It is called… _Extinguir_."

* * *

 _Term Dictionary_ :

 _Arrogante_ – 髑髏大帝 – The kanji are "Great Skull Emperor;" the Spanish means (predictably enough) "Arrogant." Baraggan's resurrección. The release command is _kuchiro_ (朽ちろ), the imperative of "to rot/decay." When in this form, Baraggan actively decays everything around him within a certain radius.

A bit of trivia: the "kuchi" in "kuchiro" is the same as the one in "Kuchiki." Byakuya and Rukia's last name literally means "rotten/decayed tree."

 _Tenken_ – 天譴 – "Heavenly Punishment." Komamura's zanpakutō. The release command is _todoroke_ (轟け), the imperative of "to roar." In its Shikai, Tenken creates various phantom body parts of an armored giant to copy whatever body part Komamura moves; for example, should Komamura swing his sword, a gigantic disembodied arm wielding a sword appears and mimics the movement.

 _Kokujō Tengen Myō'ō_ – 黒縄天譴明王 – Basically? "Black Thread Heavenly Retribution of the Vidyārāja." A Vidyārāja is a type of deity in Vajrayana Buddhism, so it's basically "this type of god's heavenly retribution, from/involved with the specific hell realm that includes punishment with black thread." It's Komamura's bankai, which amounts to a gigantic puppet-golem-thing in a suit of samurai armor that mimics Komamura's attacks, only while being way bigger and more destructive.

 _Suzumushi_ – 清虫 – "Cricket." Tōsen's zanpakutō. The release command is _nake_ (鳴け), the imperative of "to cry." It can do a couple different things, including producing a high-pitched tone that can knock someone out, or splitting into a bunch of little blades which then rain down on the enemy, but otherwise it remains basically a katana.

 _Suzumushi_ _Hyakushiki: Grillar Grillo_ – 鈴虫百式狂枷蟋蟀 – The kanji are "Cricket Hundredth Ceremony: Lunatic Shackles Cricket." The Spanish part alone comes out to "Chirping Cricket." Tōsen's resurrección. It basically makes him into a giant hairy bug. On the "plus" side, he can see, so there's that. Also comes with standard Arrancar stuff like a cero and high-speed regeneration.

 _Wabisuke_ – 侘助 – "The Wretched One." Izuru's zanpakutō. In shikai, Wabisuke doubles the weight of any object it strikes. The ability can affect both inanimate objects and living beings, and is cumulative. The release command is _omote o agero_ (面を上げろ), "raise your head." When activated, the blade loses its curve and straightens. Where a normal katana would end, Wabisuke's blade makes two 90 degree angles, forming three sides of a square, reminiscent of a hook. The cutting edges are on the inside.

 _Taimatsu_ – 松明 – "Torch." One of Ryūjin Jakka's shikai techniques. allows Yamamoto to create a great inferno with a simple wave of Ryūjin Jakka. The flames can be controlled with great precision by Yamamoto: they attack only the targets he chooses, and he has power over their intensity.

 _Ennetsu Jigoku_ –炎熱地獄 – "Flames of Hell." One of Ryūjin Jakka's shikai techniques. Creates seven or more immense pillars of flame which surround an area. The intent of this technique is to trap the opponent in the caged inferno and destroy them. The power involved can destroy everyone caught in the vicinity, including Yamamoto himself.

* * *

Guys. _Guys_. (I use this term gender-neutrally). Guess what? This story, without the notes or dictionary entries, just went over 100,000 words. This AU is pretty close to hitting 300,000, actually. (I'm like 10,000 words short, so I'll be there in two weeks, give or take). Not that quantity is a measure of quality or anything, but… I dunno. I wasn't sure I had this many words in me before I started, and when I think about all the stuff I still want to do with the AU, I'm pretty excited to see how far I get. :)

Anyway, as usual, reviews desired but not required. Thanks for reading!


	21. Chapter Twenty-One: The Limit

_Content Warning_ : Character death.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Twenty-One: The Limit

* * *

Isane was quite nearly elbow-deep in blood when Kira's message came through. Her mouth tightened; thinking about Momo's condition wasn't going to help her deal with Ikakku's injuries. Fortunately, Yumichika had finished his fight quite quickly, and was now dealing with Ikkaku's gigantic opponent while she tried to make sure the Eleventh Division didn't lose their third seat to his injuries.

Iemura had moved to reinforce the pillars with the devices the Twelfth had made to stabilize the transfer kidō should things get dicey. There wasn't a much better word for what they were now. Everyone was fighting, and from the number of reiatsu signatures she could pick out, they were outnumbered on top of that. If the Arrancar were really strong enough that one of them could do this to Ikkaku…

She shook her head slightly. This wasn't the time to think about that. She redoubled her concentration, keeping the flow of reiatsu steady through her arms. The flesh-mending kaidō was all that was left; Isane had been healing long enough that she could practically do it in her sleep. But still—there was no point in taking unnecessary risks; she gave the task the focus it deserved.

Slowly, Ikkaku's body knit itself back together underneath her. It was strange, but the fact that she'd had to patch him up so many times in the past—after practice matches or training or whatever else the Eleventh got up to—made it easier to do so now. Everyone's reiatsu was different, but she knew Ikkaku's well. Carefully, Isane passed her hands down the air just over his abdomen, skin melding closed in her wake. She'd only done a partial reiatsu restoration—she couldn't risk any more than that, or she might not have enough left for any future injuries.

There wasn't even a question about whether there _would_ be future injuries. There would. And until the triage teams managed to get organized and deployed, she and Iemura were the only healers on the field.

"Don't move around too much unless you absolutely have to," she advised. When Ikkaku looked about half a second away from protesting, Isane tried to channel a little of her captain's infamous polite menace. "Ikkaku-san. I'm serious. If you get yourself injured again, I will have wasted this reiatsu. I can't afford that. _We_ can't."

For perhaps the first time Isane could recall, it might be a good thing that the Eleventh liked to do things one-on-one. Ikkaku wouldn't interfere in Yumichika's fight. Hopefully that did turn out to be good news, and she wouldn't be rushing back here in ten minutes with another friend in critical condition.

Speaking of… she had to get a move on. Pulling off her bloodied gloves, Isane tossed them aside and sought Kira's reiatsu. He'd be nearby Momo still—but hers was so weak that Isane couldn't detect it. Not from this far, anyway.

With a small hop, she stepped into _shunpō_. She'd been working on her battlefield mindfulness, and Renji had provided several pointers on being ready for attacks even when things seemed clear. That was probably the only reason her hand was on her zanpakutō.

Which was in turn probably the only reason she survived the ambush.

A dull whistle cut through the air. Isane reacted automatically, pulling Itegumo free of his sheath and blocking with both hands. The impact was still heavy enough that her arms jarred; she absorbed most of the force by allowing her elbows to bend slightly. Sliding out from underneath the attack, she sidestepped into a reflexive counter—but her attacker easily swatted it aside.

"Heh. Here I thought I was just going to take your head off in one hit." The speaker was dressed like all the other Arrancar. He was more than half a foot shorter than her, but then so were most people. The mask he had was on top of his head, except for two really big fangs, which framed either side of his face to just beneath his chin.

Isane took a steadying breath. She wasn't really a combatant—she was a medic, and that was just the way of things. If there were a choice, she would leave this fight and go to help Momo and Kira. But she didn't _have_ a choice—she had to be both right now. "S-stand aside," she said, keeping her tone level and mild as possible. "I have no desire to fight you. All I want is to get to my allies on the other side of the field."

One side of the Arrancar's mouth pulled up. "You think I care? Baraggan-sama told me to engage, and so that's what I'm going to do. Soldier, healer, civilian—what you are isn't important. The only thing that matters is that you're going to die."

Isane frowned. "I see."

"I'm Ggio Vega—I serve His Majesty Baraggan-sama."

Baraggan? Not Aizen? Isane wasn't sure what to make of that. She also wasn't too sure the introductions were really a good idea, but something about the idea of being rude, even to an opponent, didn't sit well with her. "I'm Isane Kotetsu, fukutaichō of the Fourth Division."

"Fukutaichō, huh? I'd rather have fought a captain, but I guess you'll do for now. Show me what you've got."

There wasn't really another option, and Isane wasn't inclined to waste time. " _Hashire, Itegumo!_ "

She felt the zanpakutō's spirit respond; her sword straightened and split, two smaller blades forking out from just in front of the tsuba. The hilt in her hand cooled perceptibly; chill fog billowed off the blades—not enough to actually impede vision, though.

Vega jumped towards her, lashing out with hakuda. The kick he aimed for her neck rebounded off the flat of Itegumo's blade instead; the contact vibrated up her arms and down her spine. He could definitely hit hard.

Swinging to force him back, Isane charged a kidō in her free hand, forming a small, crackling sphere of energy. " _Hadō #63: Raikōhō!_ " The spell surged; she thrust her hand forward, hurtling the sphere for Vega's midsection. He twisted in midair; Isane gritted her teeth and pointed at the left edge of the sphere. " _Hado #1: Shō!_ "

The concussive blast hit where she'd aimed; like one stone hitting another, it knocked the Raikōhō off-course, sending it to the right—and into Vega. Her improvised calculation was a little off—she only caught his left half. His sleeve incinerated outright, along with most of the uniform over his torso. His skin reddened at the point of impact, smoking faintly. She could see his Hollow hole under his lungs, but his clothing had taken most of the damage.

That wasn't great news; if a _raikōhō_ only singed him…

He scowled openly at her; a breath hissed out from between his clenched teeth. "You're going to pay for that, fukutaichō-san. _Kuichigire, Tigre Estoque_!"

Isane raised Itegumo, crossing her arms in front of her face to shield herself from the energy expelled by the release. She swallowed—this wasn't what she came prepared for. But… wasn't it why she'd been training? She'd said that, even if only once: her being able to defeat this Arrancar might make the difference between life and death for someone else. She couldn't second-guess herself now.

Vega's release was unusual; aside from the striped uniform and heavy braid, it really only seemed to provide him with an extra attached blade on each arm. She'd been told to expect much more animal-like characteristics. Isane wondered if there might be some other technique that accounted for the difference. Shelving the thought, she decided to deal with what was in front of her.

Like those swords. The release accelerated Vega's movements—she hadn't even noticed him shift until he was right in front of her. It was all she could do to get _mostly_ out of the way of the strike—he still skewered her just inside the shoulder. Isane jumped back, pulling herself off the blade in the process. Healing kaidō on oneself were notoriously difficult; she clotted the injury as best she could, knowing there simply wasn't time for anything more. Vega was attacking again.

This time, she got Itegumo between herself and the first attack. Moving low, she interrupted the follow-up by stepping inside Vega's guard, striking him in the back of one knee with the side of her hand. He wobbled, but the joint didn't buckle, and he shifted his balance, back at the advantage.

Thinking quickly, Isane bound his legs with a hasty _hōrin_ and flashed away. She could barely detect him when he moved—he was just that quick. Fortunately, she wasn't helpless against that fact.

" _Mōshikaku,_ " she muttered.

The change was instantaneous. Everything in her visual field sharpened; suddenly she could see the individual hairs on Vega's forearms, distinctly enough to count them. The way his muscles shifted as he moved became apparent; the tension he held in his shoulders as he broke free of the bakudō was obvious. She saw him coil before he sprung; this time, she met him easily, anticipating his direction and tracking him with her improved sight.

By the time he'd arced his left-hand blade downwards, she was waiting to meet it, a _shakkahō_ in her other hand right where his chest ended up. She released it point blank, wrenching Itegumo upwards to open his guard and leave him unprotected from the blast.

"Fuck!" He jumped away, aggressively striking himself where he was still on fire in an attempt to smother the flames. "What the hell was that?"

Isane _really_ didn't see the need to explain.

"That's it." Vega lifted his right-hand blade towards the sky.

She braced for some kind of _cero_ or other energy technique, halfway to forming an _enkōsen_ shield, but though the sword started to glow, he didn't make any motion to point it at her.

" _El Sable del Tigre Estoque!_ "

* * *

Chōjirō endeavored to keep his expression neutral, though he supposed he could be forgiven for the subtle compression in the line of his mouth. He could not say whether this was truly a good idea—or rather, he could not say for certain whether Ejisai-dono would permit it. But… he could sense even through the barrier that the tide was turning against the Gotei 13. Though he had been ordered to remain here, to enforce this barrier so that the damage done to the false Karakura Town would not destroy other parts of the living world…

He regarded the eight former shinigami before him. His own thoughts on their innocence or guilt were irrelevant—both in general and in trying to assess their intentions now. But he could believe in their anger towards Aizen. Stranger alliances had been forced before.

"Very well," he said, dipping his chin to Hirako. "I advise caution, if you can find it within yourselves."

Sarugaki scowled openly. Otoribashi nodded. The rest gave him nothing by way of reaction at all. Acting in kind, he turned from them, parting the barrier in a small section so that they could enter. The curtain of golden light split and drew back, exposing the outer edge of the town—a small residential block, empty of all life.

He was about to close it behind them when the senkaimon they'd come through opened to admit one more—Tessai Tsukabishi stepped through, dressed for battle.

"Sasakibe-san," he acknowledged, glancing over Chōjirō's shoulder. "I've come to relieve you. And to inform you that Kisuke and Yoruichi will be delayed. One of the pillars fell, as I'm sure you noticed; the stabilization devices need work before they can be left unattended."

Ejisai-dono had never directly _said_ that he was counting upon Urahara-san's eventual intervention, but Chōjirō had been his servant long enough to know that it was likely nevertheless true. While the Sōtaichō was without question the mightiest shinigami who ever lived, the price of that power was that if forced to use it all, he would destroy the very things he sought to protect. Not even this barrier would be able to contain the full measure of his capability. The news that the other option might arrive too late was dire.

"We thought that, considering the circumstances, your presence on the field might make a difference," Tsukabishi continued solemnly. "No doubt the Sōtaichō ordered you to hold this position. But that was before."

Chōjirō hesitated for only a moment longer. "I understand, Tsukabishi-san. You have my thanks." Turning from the former Grand Kidō Chief, he opened the barrier again and flashed forward into the gap.

* * *

Ryūjin Jakka could produce no fire. What already was had been smothered, and something about this boy's reiatsu was preventing him from generating any more. Even bankai was ruled out, as it required the ability to draw the flames back _into_ the blade.

Genryūsai did not take this to eliminate his chances of destroying the Arrancar. But in the time it took to do so, there was no telling what havoc the traitor himself would be able to wreak. And with no other option, it seemed the child would indeed be his foe for now.

"Have you forgotten so easily?" He asked of Aizen.

The wretch tilted his head, inviting elaboration without deigning to say the words.

"Have you forgotten _why_ , after all this time, I am still the Sōtaichō of the Gotei 13? In all that time, no shinigami has been _born_ who has surpassed me. If this is what you have brought, then that fact remains true."

He held out hope that one day, one of his students would manage the feat—but until that day, he was and would remain the mightiest of his comrades. It was prudent now to remind Aizen of that as well.

Shrugging out of his shihakushō's sleeves, Genryūsai dropped into a hakuda stance. Confident that the traitor had no intention of joining the fight himself, he instead focused the majority of his attention on the childish Arrancar. "It brings me no pleasure to destroy one such as you," he said, knowing that the child likely could not understand him. "But destroy you I must."

If nothing else, he needed his zanpakutō back.

With a single flash step, Genryūsai placed himself directly in front of the boy—Wonderweiss. The momentum from the motion, he directed into his upper half, surging forward and slamming both fists into the Arrancar's side. The white armor plating on his midsection cracked with a heavy sound; Genryūsai's reiatsu pushed through it and broke off several chunks, which faded to dust in the open air.

It was then that he felt a disturbance in the barrier around the false Karakura Town, followed by several once-familiar reiatsu signatures. A hundred years, it had been, since the Central 46 condemned those eight souls to their destruction. The incident had taken another three valuable shinigami from Soul Society as well—while those three were collaborating with the Gotei 13 in this, he had not expected the eight to put in an appearance.

It didn't take long for them to arrive; the new disturbances in the reiatsu flooding the area had drawn a great deal of attention—most of the battles raging below and beside his own ceased while everyone accounted for the new factor. Immediately, six of the eight split from the group, their reiatsu changing until it resembled that of a Hollow just as much as that of a shinigami. Each of them was near or above captain-level; but it remained to be seen exactly what they would do.

A short time later, Chōjirō's reiatsu appeared on the inside of the barrier as well; he arrived at Genryūsai's side a second after the remaining two intruders stopped short of him.

"Shinji Hirako and Hiyori Sarugaki," he said gravely. With a hundred years between then and now, they had changed little on the surface. Only the expressions on their faces told of whatever the last century had been to them—the girl was barely banking her rage, and Hirako… well, he was containing his slightly better. That was all that could be said.

"My apologies, Sōtaichō," Chōjirō said, kneeling with a fist braced in front of him. "They wanted to be allowed in; I believed they might be of some assistance."

Chōjirō's judgement was steady and sound; Genryūsai knew that. So he turned his attention to Hirako instead. "May we assume by your presence here that you are allies of the Gotei 13?"

Hirako snorted, a sneer pulling across his face. "Of course not," he said immediately. "But you know… we _are_ the enemies of Sōsuke Aizen. That's good enough for us if it's good enough for you."

Genryūsai considered that for a moment, then dipped his head. The aim of any battle was victory. He was not going to turn away the means to it. "Very well then."

* * *

"Don' rush him carelessly." Shinji glanced at Hiyori out of the corner of his eyes. With the old man dealing with that weird Arrancar kid, and the others out reinforcing the Gotei 13 in whatever way they wanted, it was the two of them against Sōsuke. At least for the moment. "It's that ability of his. If ya approach him without thinking, that'll be the end of ya."

"I know." Her knuckles turned white over the hilt of her zanpakutō.

Shinji sighed. "You idiot. If you know, then relax your grip on your sword. Ain't gonna hit nothin' right that way." He swallowed; maintaining his indifference was harder just now than it'd been in a while. Maybe because what he'd been aiming for over the last hundred years was nearly in his hands? That could be it. Hiyori felt it, too—she had to. But she wasn't as good at indifference.

"Such kind words," Sōsuke commented— _his_ indifference was expressed as false politeness. It always had been. Even when Shinji hadn't known _what_ his fukutaichō was hiding, he'd known he was hiding _something._

He was better at being indifferent than all of 'em, by miles.

"Just what I'd expect from you, _Captain_ Hirako."

Hiyori sucked in a breath, her scowl pulling deeper. She was tight as a wire, frayed and halfway to snapping already.

"Hiyori," he warned sharply.

 _Don't blow this._

"However," Sōsuke continued, almost like he was oblivious to the byplay, "this whole 'if you approach him carelessly' business sounds rather… funny." He smiled, all fake sun and warmth. "It doesn't matter if you approach me carelessly or with caution… or even if you approach me at all. All of the outcomes will be the same. I'm not talking about the future—your demise will be due to those events of the past from which you already have no way of escaping."

Hiyori growled in the back of her throat. Fuckin' shit.

"He's baiting you—don't fall for it!"

"What do you have to be afraid of?" Sōsuke was pretty much talking directly to Hiyori now—Shinji could tell.

"All of you failed Arrancar already died on that night one hundred years ago."

"Shit!" Shinji lunged, trying to restrain Hiyori, but she was mad as a bull in a china shop, and she was gone by the time he made it to her spot. His heart leaped into his throat. "Dammit, Hiyori!"

She charged Sōsuke, her rage making her easier to read than a large-print book. Shinji drew his sword and flashed after her, but at that point some part of him already knew there was no preventing what happened next.

He saw it almost in slow motion; the flicker of satisfaction across Sōsuke's face as everything lined up exactly the way he'd intended it. Hiyori's mask appeared over her face; she swung hard for Sōsuke's torso. But long before she ever had a hope of hitting, Kyoka Suigetsu was there, whistling through the air above.

There was a half a second of just… nothing. No noise that he could hear, no motion that he could see. Just two people suspended in midair. Shinji hoped that second would last, because he already knew what he'd see in the one after.

But his heart thudded again in his chest, and time caught up. A red line appeared right down the middle of Hiyori, from the top of her head to her feet. Her left side slid away from her right, wet organs exposed to the sunlight for only a second before she started to disintegrate.

"Hiyori! _Hiyori!_ "

If wanting could have made it untrue, she'd have miraculously put herself back together right then. But Shinji landed out of his flash step in just enough time to close his fist over some of her dust. It was grainy under his fingers, and then it was gone.

"No…"

The rest of her drifted away on the breeze.

* * *

He felt it, when his creator killed that girl.

They felt it too—it was obvious in the way they faltered.

Anzparrejar had been hunting; that was what he'd chosen to do when his creator permitted him to choose. There were many weakened shinigami on the field already, wounded or depleted and easy pickings. But then these had interfered, and his fight had been chosen for him.

He hardly cared for the idea of killing three failed Arrancar—none of them interested him in any way. But they had placed themselves in front of him, and in order to move on to better opportunities, he must move through them. So be it.

In the moment their faces contorted into shock and grief and those unfathomable human emotions, Anzparrejar drew the heavy sword off his back, taking a single massive _sonído_ step and appearing directly behind the blonde one. His mask looked like a bird.

Anzparrejar wondered if his soul would taste like one.

The failed Arrancar was faster than he seemed; he twisted just enough that Anzparrejar's blow did not slice him in two. Instead it bit deep into the shoulder muscle, and when he wrenched, the man's arm was left hanging on only by a sliver of flesh. His blood left him in a fine mist; it thickened to a heavy flow after. Some of it spattered the side of Anzparrejar's face, warm, sticky, and metallic. He could smell it even through his mask.

He felt himself start to salivate, and swallowed automatically.

Before he could end the failed Arrancar's life with a second blow, the one with the club intervened. Anzparrejar caught the blow on the edge of his cleaver; the stark metallic screech of the weapons moving against each other was annoying. Stepping away again, he reset himself in front of all three.

"You don't talk much, do you?" the club-bearer asked.

Anzparrejar had no desire to answer. When the third one—the one with the flat mask that had angled holes in it, sent a blade of air at him, he jumped away from it and took two more _sonído_ steps to flank, hurling a line of black reiatsu from the end of his zanpakutō. It met midair with some kind of fireball from the club-man. The bird-man lashed at him with his whip, catching Anzparrejar around the ankle.

With only one hand to hold with, he could not resist when Anzparrejar kicked out, loosening the whip enough to slide it off his ankle and blocking the overhead strike from the club-man at the same time. He had to move fast to keep them from closing in on him—when they hunted as a pack like this, their teamwork was formidable.

But he also knew that all he had to do was wait three minutes or so, and they would be helpless goldfish—and he, the piranha.

* * *

" _Ute, Tiburón._ "

Jūshirō allowed Sōgyo no Kotowari's blades to rest loosely in his hands. The resurrección's release issued a burst of water and reiatsu—Harribel cut herself out of it, and it subsided. His eyebrows inched towards his hairline; it was quite the impressive amount of water.

He supposed that when _ceros_ and other energy attacks proved more harmful than beneficial, trying something new was just good strategy. He believed he'd demonstrated the necessity for that, and so the battle could begin in earnest.

A flare in reiatsu, followed by the sudden disappearance of it, caught his attention. Hiyori-chan was…

" _La Gota!_ "

His inattention nearly did him in—Jūshirō had just enough time to react to the blast of water now headed in his direction. Raising both of his swords, he compressed his reiatsu at the edges and swung forward in a double slice. The water, held together by Harribel's own energy, parted down the middle and fell away to the ground below.

Jūshirō frowned. There were other battles happening down there, as well as healing. He didn't know if she could generate enough to cause a flood, but it seemed better to finish this before he found out the hard way.

" _Tridente_." Gathering yellow energy along the blade of her transformed sword, Harribel slashed forward, throwing the reiatsu off the blade towards him. It was much more condensed than that wide-area _cero_ of hers; he probably shouldn't let himself be hit by it.

Fortunately, the exact form of the energy wasn't really an object. Leaning to the side, Jūshirō caught the bolt, redirected it, and fired back. The bright yellow was even more dazzling directly in front of him.

When he was hit square in the chest with a compressed water jet, he understood that that had been the point. He staggered backwards in the air, holding his breath as the water dispersed. It sank heavily into his shihakushō and his hair—just like any water would have.

"That was quite clever," he said honestly, pulling in an uncomfortable breath. The impact to his chest had not been kind to his lungs, but he went to pains to make sure he had enough air to speak without any wavering. "And here I thought you hadn't even figured out how I was shooting _ceros_ at you."

"Redirection," she said flatly. "It's quick; if I hadn't blinded you, you'd have made it away in time."

The corner of his mouth pulled up. "A generous estimation of my capability; thank you."

She furrowed her brows—it was difficult to say with the lower half of her face covered like that, but she seemed perhaps a little frustrated. Jūshirō felt a familiar itch in his chest—he wasn't sure he had too much longer at full capacity. Pointing the right-hand sword forward, he decided to accelerate the fight before he lost it.

" _Hadō #73: Sōren Sōkastsui._ " The twin lances of flame burst from the end of the blade, driving through the air towards Harribel.

As expected, she immediately called up more water to extinguish them. The two attacks met with a massive sizzle—a cloud of steam soon obscured the area between the combatants. Jūshirō held his breath and dove through it. One _shunpō_ step put him beside her; Harribel's eyes rounded. He'd been so stationary up to this point that it was doubtless a surprise that he bothered to move. Still, she recovered quickly—the broadsword she carried blocked his left-hand attack, and she twisted away from the right.

" _Hirviendo!_ "

Quite suddenly, all the water soaked through Jūshirō's clothes and hair burned; he pulled in a gasp too sharply. That immediately set off the coughing fit he'd been trying to hold at bay—great, wracking heaves shuddered in his chest. Harribel moved away, capitalizing on his moment of weakness to send another, larger blast of water at him.

Jūshirō, weakened by the burns and his lungs, was nonetheless long accustomed to pain. Pushing through it, he forced up his left hand, catching the water in the same way he'd caught the _cero_. Everything was fundamentally energy—this was simply energy in a different form.

He didn't get all of it—he could feel some of the water blow past him. But he caught enough. Between shudders, he lowered one arm and lifted the other, actually dropping the sword in his left hand. The water issued from the end of his right sword, headed right for her.

" _Hadō—_ " He sucked in air, losing it immediately to the need to cough. Jūshirō tasted blood in his mouth, and tried again. " _Hadō #63: Raikōhō._ "

Harribel likely had nothing to fear from her own water—he'd guessed she might be able to disperse what he sent back at her. But the lightning spell on its heels was another matter; accelerated by the fluid it passed through, it struck her square in the chest.

She fell.

Jūshirō's vision swam—it was too much. He'd done too much. The landscape in front of his eyes flickered, and went dark.

* * *

"Mind if we cut in?"

Izuru had no idea who these people were, or what the story was with the Hollow-like masks they wore, but considering his condition, he certainly wasn't going to complain if they wanted to help. He still had no idea if Momo was all right—something must be holding Kotetsu-san up, or she'd have been down there already.

"Be my guests," he said, unsure exactly what to expect from this. One of the women was dressed mostly in white, with an orange neckerchief or something. Her mask reminded him of an insect. The other had a long braid, a longer spade-type pole weapon, and a mask with a cross in the middle.

"Mashiro Kick!" the first one called, sailing forward with her leg thrust out to hit Ayon.

"Don't—" Izuru started, but it was a little too late.

Her hit landed, forcing Ayon's shoulder slightly back. That only seemed to draw its attention, however—almost immediately, it grabbed her out of the air in one massive fist. She squirmed in its hold; Izuru resigned himself to flashing forward and trying to weight the arm down.

" _Nijū Ichijō Tonbokudari!_ " The second woman used their positioning to target Ayon's arm with a series of thrusting attacks with the spade, lunging forward and hammering away at Ayon's outstretched limb.

The creature swatted her away with enough force to put her through several nearby buildings, but his arm was bleeding. Izuru decided that getting the other one free was still the best option and stepped into _shunpō_ , jumping with enough force to throw himself over the wrist. Orienting his body in midair, he tried to ignore the vertigo that came from being upside down with air rushing by on all sides, slashing quickly with Wabisuke to weigh down Ayon's hand.

He got three hits in before he passed by; the creature bent forward under the unfamiliar heft of his own body. That was, essentially, what he'd been looking for the opportunity to cause; Izuru flashed upwards towards Ayon's neck for the familiar guillotine maneuver.

Only to find himself staring down a gaping maw far bigger than it should have been. The mask it wore didn't cover its face at all—more like its _nose_. Ayon lunged forward, its teeth closing over Izuru's foot and crunching bone.

He choked on air, lacking enough of it to shout. Ayon lashed its head back and forth like a dog; Izuru heard at least two more snaps, but he couldn't distinguish the pain of one from the pain of the next. The creature let him go for some reason; he dropped like a stone to the ground.

From this angle, he could see why—the second woman had slashed broadly across its back. Finally, it let the first one go; though the blood staining her white jumpsuit indicated more injury than he could otherwise see, she still flashed forward. This time, she landed a punch on Ayon's mask at the same moment as Izuru hit the ground.

He was powerless to do much but watch after that—they fought with a power he could scarcely understand—it was probably about what he'd expect a captain to have, but… some of the energy was definitely Hollow reiatsu. Were they Arrancar? If so, why fight their own kind?

Ayon swatted at them like they were flies; but they were definitely biting him. Izuru was almost certain they'd succeed in bringing the chimera down.

Until their masks cracked off their faces. Much of their reiatsu suddenly disappeared—abruptly, they were no stronger than him.

The results were immediate. Ayon grabbed both out of midair and threw them onto the ground. The concrete beneath them cracked and shattered with the force of the impacts, and the massive giant raised one of its feet to crush them.

" _Bakudō #61: Rikujōkōrō!_ " Izuru scrambled to help, firing off the kidō from the ground where he lay, unable to move much.

The beams of light slammed into the chimera, holding it in place just long enough for the one with the polearm to set it against the ground and angle it up. When the bakudō broke, Ayon impaled his own foot on the spade end, all the way down to the ground, where the girl in white pulled her friend out from underneath the danger zone.

As if in slow motion, Ayon tilted to the side, topping like a building—and _into_ several of them. When the dust settled, the creature did not stir.

* * *

 _Term Dictionary_ :

 _Tigre Estoque_ – 虎牙迅風 – The kanji are "Tiger Fang Swift Wind." The Spanish comes out to "Tiger Rapier." This is Vega's zanpakutō. The release command is _kuichigire_ (食い千切れ), the imperative of "to bite off." As far as resurreccións go, it doesn't actually change his appearance that drastically, though it has a special technique, _El Sable del Tigre Estoque_ (虎牙迅風·大劍), which in kanji is "Tiger Fang Swift Wind Great Swords." As the original Spanish from canon is… weirdly done, I changed it so the words mean "The Saber of the Tiger Rapier," which still isn't that sensical but at least counts as grammatical, I _think_.

 _Itegumo_ – 凍雲 – "Frozen Cloud." Isane's zanpakutō. The release command is _hashire_ (奔れ), the imperative of "to run." Since we get no details on any of its abilities in canon, I've kept the shape and made up the rest myself.

 _Mōshikaku_ –盲視覚– "Blind Sight." One of Itegumo's shikai abilities. By using this ability, Isane is able to enhance her senses to the point of being able to perceive things well beyond normal limitations. She can, for example, see in utter darkness or hear the way someone's blood is moving through their body. The data can be overwhelming, and as such, she usually only enhances one sense at a time; the ability is useful for diagnostic purposes and finer healing abilities as well as more violent applications, such as detecting the minute motions a person's muscle makes before the movement is otherwise visible. With that information and her knowledge of how the humanoid body works, she can predict how her opponents are going to act a few seconds before they actually do so. This leads to the common misinterpretation of the skill as either mindreading or precognition.

 _Tiburón_ – 皇鮫后 – The kanji are "Imperial Shark Empress," and the Spanish is "Shark." Harribel's resurrección. The release command is _ute_ (討て) the imperative of "to destroy." In this form, Harribel's sword gets a lot bigger and more solid, and she can control water with it, as well as use various energy attacks.

 _La Gota_ – 戦雫 – "War Drop," are the kanji and the Spanish is just "The Drop." Harribel condenses a large amount of water around her blade before firing it as a blast which resembles a shark tooth.

 _Tridente_ – No kanji here, just the Spanish, which comes out to "trident." A technique in which Harribel produces a large burst of bright reiatsu from Tiburón's blade. She uses it to cut Hitsugaya's replica in half in canon.

 _Hirviendo_ – 灼海流 – The kanji are "Burning Current." The Spanish is "Boiling." A technique in which Harribel heats any water which comes close to her sword. As Ukitake was already soaked here, she basically just boiled the water in his clothes and hair.

 _Nijū Ichijō Tonbokudari_ – 二十一条蜻蛉下り – "Twenty-First Article: Dragonfly Landing." A shikai technique of Lisa's; she stabs an opponent multiple times in quick succession.

* * *

Whew! Another chapter down. And... another death to add to the tally. It seems likely that without Gin to preempt by bisecting Hiyori in a _survivable_ way that Unohana then somehow fixes... she was pretty much a goner. :/ You just don't recklessly charge a dude like Aizen.

Probably out of all the parts of this chapter, I had the most fun with Isane. Making stuff up for her shikai was cool; I might have to find an excuse to use its other technique, too. :)


	22. Chapter Twenty-Two: Burnout

_Content Warning:_ Character death, and violence as usual.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Twenty-Two: Burnout

* * *

"Komamura… you are more hideous than I imagined."

It wasn't as though Sajin had never heard similar insults. Even if he didn't draw disdain, he drew curiosity, questions he grew tired of answering. Both were the reasons for the helm he usually covered his face in.

With Kaname, there had never been any need.

Apparently, things had changed even more than he thought. His friend could see—and _that_ was what he thought. Sajin shut his eyes for just a moment, batting aside the familiar shame and hardening his resolve. Kaname's heart—something that once seemed so transparent—was opaque to him now. Words like _justice_ didn't mean anything nearly the same from his friend's mouth as from his. Their fates had become irreconcilable.

Drawing back his sword, Sajin bore down with it like a guillotine. Though his whistled dully through empty air, his bankai's was on track to cleave Kaname in two. Much to his shock, his arm stopped short of completing its arc as the katana in midair fell into Kaname's outstretched hand. He caught the blade, his other insectile arms lifting and tracing circles in the air.

" _Los Nueve Aspectos_." From the lime-colored circles boomed a thunderous noise; after the first one, Sajin couldn't hear anything, his sensitive ears deafened at least temporarily by the blast.

But he could feel the ones that followed, and all of them hit Kokujō Tengen Myō'ō, dead-center in the chest. Sajin's own ribcage buckled, snapping in several places and pressing into his lungs. His next breath was a labor—accompanied by a bursting pain he couldn't remember ever feeling before. It laid him out flat on the ground; an eyeblink later, Kaname stood over him.

"Shall I put an end to this, Komamura?" Kaname's voice sounded strange, like it was coming through water. Twin pinpricks of green light gathered, one in front of each of his protuberant bug-eyes. As they grew, they merged—a _cero_ , then. The person he'd once considered his best friend was going to end him with a _cero_.

Something in Sajin railed against that; he realized he was still holding Tenken only when the hilt resisted his effort to clench that hand into a fist. His bankai was destroyed, and the wound that had been inflicted upon him was no doubt fatal. He could feel the blood pooling in his lungs, he was sure of it. Each of his breaths wheezed; his vision was already starting to fade out.

Vision. Kaname could see, now—and soon, Sajin would not be able to. But if he could see… why was he apparently so oblivious to Tenken's presence?

Something struck Sajin, then—though he could see, Kaname was less _aware_ than he'd once been. Perhaps…

So that was how it was to be. Very well, then.

Pooling everything he had left into one moment, Sajin pulled himself up off the ground, stabbing forward with Tenken. His bankai had been destroyed, but he still had shikai, and a spectral arm appeared where his own left off, thrusting a giant sword. It hit Kaname right between the eyes even as the _cero_ went off, engulfing Sajin in its light.

Their time in this life ended as their time in the Gotei 13 had begun—together.

And neither of them saw anything at all.

* * *

This second form of Vega's was… Isane threw herself into _shunpō_. The edge of his blade scraped the back of her shikahushō, cutting into the first layer, but not the second—he missed _that_ closely. Even though she could, quite literally, _see_ his attacks coming, their strength and speed was still insane.

He said he'd have rather fought a captain. She expected he might have been able to challenge one. So how was she supposed to stand up to him, much less defeat him and press forward?

" _Bakudō #39: Enkōsen._ "

Vega's second blade crashed into the shield she summoned, cracking it down the center. She abandoned it and jumped clear, tangling his legs with a _midoriami_. The problem was that nothing seemed to hold him long enough for her to also do damage. She was at best merely hindering him so that he couldn't kill her—but if she failed to do that even once, she was in serious trouble.

Compressing her lips, Isane decided that there was no choice. She had to attempt her other shikai technique, difficult to deal with as it was, or she wouldn't survive. Wanting to conserve her energy to heal was one thing—but she couldn't heal _anyone_ if she died.

" _Usugime_."

In her hand, Itegumo burst apart, forming into a cloud of chilly fog. As she fed more of her reiatsu into the zanpakutō, he expanded his radius, billowing outwards to envelop a large swath in thick, nearly impenetrable mist. But the fog was still Itegumo, and everything that it touched, Isane _felt_ , in a way that was difficult to put into words.

She knew the exact direction and force of the breeze in fake Karakura town, because of the way it pressed against the edges of the obscuring cloud. She could feel her own movements, down to the smallest twitch, both because of her own nerve endings and proprioception and also because of the way they stirred the mist. She knew the shapes of all the pieces of rubble Itegumo touched, and the contours of every wall.

It was overwhelming. With great effort, Isane focused in, blocking out the irrelevant information in favor of what she was really looking for. It wasn't difficult to find Vega; he thrashed around in the fog, trying to disperse it so he could see. His motions stirred it like the flailing of a man drowning stirred a lake. She knew, without being able to see, that his left arm was above his right currently—and that he focused on the space in front of his eyes, because he was more desperate to regain his sight than his dimmed hearing or sense of smell.

And because she knew exactly where he was, Isane concentrated the fog there, pulling it in and packing it denser and denser into one specific place—the one where Vega was. The sensations grew more acute; she tried to ignore them, focusing specifically on the area around his nose and mouth. As Vega breathed, he pulled more and more of the fog into his lungs—at a faster pace as he tried to break free of the cloud that followed his movements.

When she decided there was enough to work with, Isane exhaled. A pulse of reiatsu condensed the fog in his lungs into water. Another turned it into ice, and she pulled it free of his body with a sharp hand motion. The sound of blood spattering on the ground, followed by chunks of flesh, didn't turn her stomach near as much as _feeling_ it did. She swallowed, then called the fog back into blade form. Itegumo solidified in her hand; in the stark light of day, it was easy to see Vega, collapsed facedown in a puddle of his own blood.

The weakness settled into her muscles immediately; using Itegumo like that was not something Isane had practiced often for obvious reasons, and it had put a serious dent in her reiatsu. But there was still healing to be done—and where Kira and Momo were seemed like the best place to start.

* * *

"Ōmaeda, will you stay here and make sure Iemura is safe to calibrate… whatever those are?" Shūhei was more artist than scientist. All he really understood was that the devices Iemura had planted in the ground were supposed to make up for the fact that one of the pillars had been destroyed.

"Uh, yeah. Sure." Ōmaeda didn't really _look_ sure about that, but Shūhei thought he saw relief flash across his face for a second.

Honestly… he couldn't blame him. This fight was… he wasn't certain what to think. Captain Tōsen's reiatsu had disappeared a few minutes ago, along with Captain Komamura's. Whether they were dead or just incapacitated was hard to tell—trying to sense anything with Aizen around wasn't easy.

"The rest of us should get going. I think Isane-san is headed towards Hinamori and Izuru—she might need some help." Something had changed over there, too, but there were way too many unknown reiatsus to make sense of it from this far away. Shūhei glanced at the other two.

Yumichika was a little bloody, but otherwise fine; he nodded. Ikkaku was in worse shape reiatsu-wise, but no longer had any open wounds, thanks to Isane. Shūhei himself was probably in the best shape of anyone here, but he wasn't sure how much of a difference that would make. He took a deep breath—it smelled like blood and ash. The latter was almost certainly the Sōtaichō, but the flames weren't visible anymore.

The three of them moved into _shunpō_. Shūhei tracked Isane, figuring that she'd get them closer to where the fights were. She probably had better senses than he did, and she was closer to the rest of the action besides. A big patch of blood on the ground marked halfway there or so; whatever or whoever had made it was long gone.

The three of them arrived in time to see Isane raise her zanpakutō to fend off a blow from a one-armed Arrancar—two more were close by.

"Isane-san!" Shūhei drew Kazeshini from his waist, stepping in to head off a flanking attempt from the second Arrancar. She only had one arm as well—in fact, that seemed to be the case for all three of them.

He ducked under the swing of a white-scaled snake tail; the Arrancar it was attached to hissed when he left a thin slice in the underside of it. Ikkaku and Yumichika jumped into the fray with the typical headlong recklessness of the Eleventh; at least it was three-on-three—that should keep Isane out of it.

Shūhei jumped away from his opponent, landing on a support beam that must once have belonged to a building that had since collapsed. A whole area of the fake town had been razed here—almost like something gigantic had fallen on it. Whatever it might have been, there was no sign of it now—but he could see Hinamori, Izuru, and two people he didn't recognize, all in various states of injury. None of them looked conscious, but they were still there, so they had to be alive, at least.

The snake Arrancar seemed to have been hit with Wabisuke a few times already—she had to drag her tail behind her to reach him. Shūhei sidestepped as she threw both arms out towards him. When several snakes emerged from her sleeves, he was glad he'd chosen that instead of blocking.

He hated this part. " _Kare, Kazeshini_." As soon as the poles of his zanpakutō were in his hands, Shūhei dropped one, gripping it instead by the chain between them, and slowly started to spin it. The dull whistle of the blades on the ends slicing air grew higher-pitched as he increased his speed; flashing forward, he flung it halfway through the step.

The weapon at the end of the chain served as a weight, wrapping it several times around the Arrancar's throat. Yanking back on the chain with his free hand, Shūhei bent himself through the air, slingshotting his body back around to where she was with the force of his _shunpō_ behind him. With all that torque, he didn't have to swing the second blade as he passed—he just extended it and let momentum do the rest.

The Arrancar's head parted from her neck, landing on the ground just after he did.

* * *

Shinji struggled to keep a lid on his temper. Just because Sōsuke hadn't taken advantage of… of Hioyori's death didn't mean he wouldn't try to do something if there was another lapse of attention. He had to compartmentalize. He and the others… they would have to do their mourning later. It wasn't fair, it wasn't _right_ , but it was the situation they were in.

Being a captain of the Gotei 13 hadn't been all for nothing—it had taught him what he needed to know to survive in circumstances like this, after all. So he pushed away all the thoughts, all the emotions connected to what he'd just seen, and focused instead on the matter at hand.

Sōsuke didn't seem to be paying much attention to him; instead, he was looking at the old man and Sasakibe, who were fending off that creepy kid Arrancar. Something about that was fuckin' messed up, but Shinji couldn't bother with that any more than he could afford to focus on anything but his former fukutaichō.

"Don' you ignore me," he sneered, feeling his lip peel back from his teeth. "No matter how strong ya've gotten, you must still have some misgivings about this. Ya said it yourself a hundred years ago: I didn't open my heart to ya, I didn't give you any information, and I didn't try ta get to know ya." He adjusted his grip on his zanpakutō, lifting the blade and pointing its end right between Sōsuke's eyes. "Which means… you know nothin' about my zanpakutō's abilities, do ya?"

Well, he had his attention, now. Sōsuke's gaze swung back to him; Kyoka Suigetsu was still loose in his grip. Still dripping red. Hiyori's red.

"If you believe that _that_ sword is the only zanpakutō capable of completely controllin' a person's senses, then yer dead wrong." Adjusting his grip, he swung his sword in a circle. " _Taorero, Sakanade._ "

The sweet scent of his initial release permeated the air immediately around them. Shinji allowed himself a mirthless smile. "Welcome, Sōsuke, ta the inverted world."

* * *

How disappointing.

The former Captain Hirako's zanpakutō was interesting for all of about thirty seconds. But once Sōsuke had figured out the trick to it, it became almost laughably easy to avoid. On Shinji's second pass, Sōsuke simply worked around the perceptual difficulty, flaying open his left side with a stroke from Kyoka Suigetsu. It was rather overconfident of his ex-superior to simply assume that such a ploy could not be overcome. He'd left open his guard in consequence.

"And here I was intrigued," he mused. "But it's nothing more than an optical illusion. A children's game."

" _Takaoni_." The new voice came from above at the same time as a shadow passed overhead. Sōsuke sidestepped the downward stroke of a heavy curved blade, flashing away from the follow-up.

"Children's games can get pretty ugly, Sōsuke-san," Kyōraku noted, tipping his head back.

"My, my." Sōsuke flicked blood off his zanpakutō's edge. "That was an impressive concealment kidō. I suppose I should be expecting my Primera Espada to ambush me soon as well?"

The blunt metallic barrel of a gun pressed against the back of his head. Starrk's reiatsu reappeared on the field in the same moment. "Something like that," the Arrancar drawled, his tone just as apathetic as ever.

Sōsuke felt the gun shift ever so slightly as Starrk depressed the trigger, firing one of his dark blue _ceros_. He leaned to the left—the blast blew past his head, missing by inches.

"Sorry to cut in, Shinji-san," Kyōraku said, "but you looked like you could use a little help."

Finally—a strategy. Not that Sōsuke expected it to be a challenging strategy, but considering the time they'd been absent from the field, it was fair to assume that they'd managed to put _some_ kind of plan together. Well… if nothing else, it would pass the time. Between the three of them, the power involved was not inconsiderable, either.

Perhaps a field test of the Hōgyoku's capabilities was in order.

"By all means," Sōsuke invited. "Please, _do_ come at me all at once."

* * *

Suì-Fēng let her shikai disperse, returning her zanpakutō to its wakizashi form. She wished she could say she'd done that because she knew she'd need it—but the truth was she was panicking so badly she'd lost all grip on the release. Baraggan—that Arrancar had done… _something_ to her. She'd passed too close to him, and now skin, muscle and blood were dissolving off her arm, like the process of rot sped up so she could _see_ her bone being exposed: fingertips, hand, forearm nonono—

Cold reason reasserted itself; it was too late for her liking, but maybe not too late to save her life. Suì-Fēng pressed the blade of her wakizashi into her bicep, cutting through the muscle and then applying enough reiatsu to push it through her bone as well, until her whole arm was gone, dropping from her body at the same time as the marrow whittled away into dust.

Blood gushed freely from the stump now; she wished she could say this was the most painful thing she'd ever experienced, but adrenaline was dulling it too much for that to be true. Maybe it should be, but it wasn't; she pulled her sleeve tight over the wound and tied it off. There was nothing else she could do right now.

She finally got her pathetic trembling under control in enough time for Baraggan to _laugh_ at her: a cold, rumbling chuckle of _amusement_.

"You see?" He said. "Even shinigami are afraid to die. Such a pretentious thing you call yourselves— _gods_ of _death_."

Suì-Fēng pulled hard breaths in between clenched teeth, switching her grip on Suzumebachi and releasing her again. She wasn't sure how much good it would do, considering the fact that she couldn't even get close enough to _touch_ Baraggan without losing her other arm, too, but…

"Perhaps I could be of some assistance."

Suì-Fēng's eyes slid to the newcomer—she'd felt him approaching but been content to ignore him. He'd changed his hair, she decided—something she probably wouldn't have noticed if she hadn't used to know him as well as she did. But other than that, Hachigen looked almost identical to himself a hundred years ago. She knew the same couldn't be said of her.

She turned away.

"Please, Suì-Fēng-san. I know you have no reason to trust me or cooperate, but surely you will concede that this situation demands a change of strategy."

She clenched her teeth harder. She'd be changing her strategy, all right—but he had nothing to do with it. "I have no reason to even talk to you, traitor scum," she replied sharply, using her anger to push down the pain.

Baraggan didn't seem like the kind to press his advantage—he liked to gloat too much to hurry things along. That was good, since bankai took some time to prepare.

"You must know by now that isn't true," Hachigen chided quietly.

Suì-Fēng's nose twitched. She swore for a second that she could smell warm tea, hear the sound of his shihakushō rustling together as he poured for the both of them. Some rainy afternoon, when his boss and Yoruichi-sama and _that dolt_ had left them both behind to do… whatever they did. Someplace no one else could follow.

She didn't want the memory, but she had it.

"Go away, Hachi," she ground out, reaching into her uniform for the heavy, metal-woven fabric she'd need to anchor herself.

"I won't do that, Suì-Fēng-san," he replied evenly. "But I will distract him while you prepare your next move." Calmly, he formed the first hand-signs for a complex kidō of some kind, no doubt.

She pressed her lips together. Fine. If he wanted to help, let him help. She could use a distraction anyway. "Don't… get too close to him," she warned, flashing away.

It took her several minutes to get herself anchored with only one hand to tie with, but she managed to wrap the fabric around a building that was not currently halfway to falling over; the other end was tied around her middle. Suì-Fēng really hated her bankai; it was a damn disgrace to her division and everything she stood for as a combatant. This was the kind of thing one of those idiots at the Eleventh should have to put up with, not someone like her. Nevertheless, circumstances demanded that she use it. At least it had one thing going for it: range.

By the time she got high enough to see what was going on with the other two, it looked like Hachigen had closed Baraggan into a bunch of different enclosures of some kind. She'd never seen it, but she thought it might be the four gates kidō combination.

"He's rotting it from the inside," he said, moving to her side so as to not yell, she supposed. "But it will hold long enough to aim, and he shouldn't be able to move far from your trajectory."

She wondered how he even knew what her bankai was—she'd still been training for it when he'd left Soul Society. But of course, whenever someone knew something they shouldn't, she could usually expect the root cause to be the same. Damn dolt.

"Hmph," she grunted, raising her arm. "We'll see. Bankai: _Jakuhō Raikōben_."

The blowback from the release alone was enough to send her staggering a couple of steps; the debris it whipped up stung her cheeks. Hefting the large launcher onto her shoulder, she looked into the sight and adjusted her aim, grunting softly when she had to change the angle.

"All right," she said. "Give me a gap in that kidō of yours."

She heard the rustle of fabric that accompanied his nod, and a hole appeared on the side they faced, in the white wall. Suì-Fēng made sure she had it, then fired.

The recoil nearly put her _through_ the building she'd tied herself to—her feet lost purchase on the air as she was thrown back shoulder-first. _Tsk_ ing, Suì-Fēng redoubled her _shunpō_ , trying to gain enough traction to slow herself down. She redirected her force sideways so she went around the structure instead of through, but she was still ultimately stopped by the pull of the ginjōhan fabric.

Dismissing her bankai, Suì-Fēng flashed back to the scene, noting that Jakuhō Raikōben had put a crack in the far side of the enclosure. They had to have gotten him—it was a direct hit, and he'd had nowhere to go.

"Unforgivable."

Suì-Fēng's eyes rounded; beside her, Hachi pulled in a sharp breath. That was definitely Baraggan's voice.

"It can't be," Hachigen murmured.

"It is unthinkable that you could inflict such severe injuries on me… you damn _ants_!"

The smoke from her bankai's detonation cleared; Suì-Fēng squinted. Baraggan's skull had a chunk missing that included the entire left eye socket, but…

"Regret your insolence and turn to dust!" Reiatsu exploded outwards towards them in two black columns; probably more of that death-fog.

"Suì-Fēng-san, get behind me!" Hachigen raised a hand to his face, pulling down an ornate, tusked Hollow mask; his reiatsu changed to match.

For a split second, she hesitated. That power was the power of her enemies—no friend of hers would use it. But the other option was death by disintegration; that alone was enough to make her choice for now. She flashed behind him, remaining in his shadow as he pulled up a large barrier, absorbing the impact and leaving them both, thankfully, not dust.

"How impudent! Pretending to be a Hollow? Do you not know who I am? I am the Emperor—Baraggan Louisenbairn, _the God of Hueco Mundo_!"

The barrier in front of them cracked; Hachigen shifted his body so that he was entirely in front of her, even as the black reiatsu broke through, hitting him in the mask and one of his arms.

"Hachi, no!" Suì-Fēng braced his back with her remaining arm, curling her fingers into the back of his jacket and trying to pull him along with her in a flash step.

"In this world, my power alone is absolute!" Baraggan crowed, heedless of their efforts. "All other things are equal in their puniness."

"Thank you, Suì-Fēng-san," Hachigen murmured, righting himself even as his mask cracked off and his right arm continued to disintegrate.

"If you don't—" she started; he cut her off with a nod.

"Behold! In my cavernous eyes, your lives and those of ants are exactly the same!"

Hachigen formed a kidō seal in his hand—Suì-Fēng was surprised when he enclosed his own forearm in it and severed the limb. His arm wound up in a yellowish box—another capped the end of his elbow, preventing bleeding, from the look of it. He smiled softly at her; his forearm disappeared.

It was only then that Baraggan stopped ranting long enough to notice that they were no longer in immediate danger of dying. "What did you do with your right arm?" he demanded.

Suì-Fēng figured it was a legitimate question.

"I humbly gave it to you," Hachigen replied. Not a second later, Baraggan let out a hoarse shout as his body began to crumble.

She was confused—until she saw the arm in the Espada's middle. Transport kidō—it had to be.

"As you say," Hachigen continued quietly. "Your power is absolute—which means it also affects you. Inferring this was a risk, but it pleases me that my reading of the situation was not incorrect."

"Damn you, you ant!"

"Please," Hachigen replied, "forgive our impiety… God of Hueco Mundo."

* * *

Anzparrejar clenched his hand around the new cut on his palm. The sting was little more than an insistent reminder—that he'd been wounded and that even ants could bite.

Not that he'd forgotten.

The club-man's oversized weapon clanged off the edge of Anzparrejar's cleaver, sending him a step backward with the recoil. They'd been holding their own for a few minutes now, but they did not have much time left. He knew this with great certainty: for as long as they called upon the powers of Hollows, all he had to do was defend, wear them down. When they lost those powers, however, matters would be quite different; their numerical advantage wouldn't mean anything.

Swinging his blade, Anzparrejar gathered reiatsu onto the edge, charging the black _cero_ and firing it from the point on the end. The beam lasted for long enough that he could sweep it over a larger area, and he did, forcing all three of them to get back away from him. For now, it was better that he not take unnecessary chances—with that cutting wind especially.

But as his creator had promised, their Hollow powers were temporary; it didn't take long before their masks cracked off their faces, fading away. How long it took until they would be able to use them again didn't really matter.

They would be too dead to care.

Leaping into _sonído_ , Anzparrejar brought his sword up and over his head, gripping it with his uninjured one and his cut one both; he brought the blade down in a fast, heavy swing. Slowed by the decrease in his reiatsu, the club-man stood no chance of getting away—the zanpakutō sliced deep across his belly, halfway to disemboweling him with a single stroke. He fell, only a weak flicker of reiatsu giving away the fact that he lived still. At least for a little while.

The element of surprise gone, Anzparrejar knew they would try to adjust tactics. Indeed, the man with the cutting wind flung more of it at him, backing up in the process to give himself more room to maneuver.

Perhaps he believed that if he did that, he would be able to see the attacks coming.

Such misapprehensions were better corrected with actions than words.

* * *

Electricity crackled along Gonryōmaru's length—Chōjirō had discovered that the strange, childlike Arrancar's abilities to absorb flames did not extend to attacks using other elements. Or at least, not attacks using lightning.

"Please, Ejisai-dono; allow me to assist you in this."

The Sōtaichō was not the kind of person who regularly allowed others to interfere in his battles. But he was also a commander, a superior officer; this was a chance for Chōjirō to do what he had long ago sworn to do. "If your Ryūjin Jakka cannot reach this Arrancar, then allow Gonryōmaru to be wielded in his stead."

He was Ejisai-dono's right hand—this he had sworn.

"Very well," the Sōtaichō replied. "You may handle this matter on my behalf." His eyes drifted upwards—Chōjirō knew he watched Kyōraku-san and his allies contend with Aizen.

He bowed anyway, shifting his attention to the large, oddly-shaped creature that this Arrancar had become. It was utterly despicable, what Sōsuke Aizen had done to this child, but Chōjirō knew of no way to undo it. Perhaps, if sent to the next life, he would be able to regain what had been robbed from him. It was a thing worth hoping for.

The Arrancar lurched towards him; Ejisai-dono had already put massive cracks in his… _carapace_ might not have been the right word, but Chōjirō knew no other way to concisely describe the quality of what must have once been skin. Setting his mouth into a grim scowl, he stepped into _shunpō_ , gripping Gonryōmaru in one hand and thrusting at the end of his charge.

His opponent heaved away from the edge of the blade, but Chōjirō seamlessly swapped tactics, pushing with his reiatsu instead of his arms and focusing it on the end of the rapier. " _Raisho_."

The energy, concentrated as a tiny yellow point at the edge of the blade, lanced straight outwards, colliding with one of the existing cracks in the Arrancar's body. The carapace was tougher than Chōjirō had imagined; even a direct hit did little more than to flake off a few additional pieces. Perhaps simply attacking the shell was not the wisest move—the vents on his shoulders and hips may make better targets.

"Aaaaa." The Arrancar listed slightly to the side, blinking at him with uncomprehending eyes.

Chōjirō felt something uncomfortable settle heavily in the pit of his stomach—ah. Remorse. Not unexpected. He swallowed thickly, furrowing his brow and aiming Gonryōmaru again, this time for one of the vents. The plan changed when a violet light started to gather in front of the Arrancar's mouth—Chōjirō grimaced and shifted his rapier's angle, firing the second _raisho_ into the _cero_ as it formed. The two bursts of reiatsu met with a cracking sound; the _cero_ dispersed into the air. His _raisho_ hit too weakly to do any damage, a result of the force taken out of it by the clash; it burst apart against the Arrancar's hierro.

Bounding aside with _shunpō_ , Chōjirō charged another _raisho_ with his right arm and a kidō in the other. When the Arrancar split his shoulders into several new arms, he nearly faltered, but simply switched the kidō instead.

" _Bakudō #63: Sajō Sabaku_." The bright golden chain of the spell shot forward from his closed fist, winding around all of the Arrancar's arms. He held onto the other end of it, touching Gonryōmaru's blade to it. " _Raisho_." The lightning traveled along the kidō chain; and Chōjirō released a second bolt right behind.

That seemed to do the trick—one of the vents in his foe's shoulders blew out entirely. A ripple of powerful reiatsu issued outwards from his body. Chōjirō pulled back on the chain, seeking to tighten it and keep control of the Arrancar's movements. The reiatsu didn't feel like it belonged to a Hollow. In fact, it felt nearly as familiar as his own. As though it were—

The _sajō sabaku_ burst with a loud shattering sound, almost like glass. A second wave of the familiar reiatsu churned outwards, escaping confinement and permeating the area in… heat.

It was fire.

Ryūjin Jakka's fire was still contained within the creature's body, and it was not going to remain there for much longer.

Chōjirō pulled in a deep breath. There wasn't a bakudō in existence that stood a chance of containing an explosion like that. The only way catastrophe might be prevented was if he could bring all of his reiatsu to bear in holding it close to the ground when it detonated. He shifted, rising onto the pads of his feet to spring forward.

If this sacrifice was demanded of him to save his comrades, then so be it.

He leaped.

" _Shō_!" The Sōtaichō's voice was like a crack of thunder. A heavy impact slammed into Chōjirō's side, knocking him far off his course.

No—if it wasn't held back, then—

"Ejisai-dono!" Powerless to interfere, Chōjirō watched the Sōtaichō leap forward, covering the broken vent with his own body.

The explosion was massive; Chōjirō felt the sharp burning sting of his eyebrows and mustache being singed near to nothing; hot air gushed past his face, blistering his skin in its wake. A column of fire erupted from the spot, blocked from rising by Ejisai-dono's body and reiatsu. Diverted, it ate along the ground, consuming everything in its path—until the block faltered and it surged upwards, too. Like an angry red scar on the sky. Like the very mark he'd long ago placed on the Sōtaichō's brow.

But it was a fraction of what it could have been, and when it receded to smoke and ash, no trace of Ejisai-dono's reiatsu remained. Not from Ryūjin Jakka's flames… and not from the Sōtaichō's body.

Impossible.

Impossible.

And yet—

* * *

 _Term Dictionary_ :

 _Los Nueve Aspectos_ – 九相輪殺 – Kanji for "Nine Pagoda Finals Kill." The Spanish is "The Nine Aspects." One of Tōsen's resurrección techniques. He draws circles in the air with his hands, and then they issue a sonic blast, basically.

 _Usugime_ –薄絹 – "Veil." The word refers to either veil in the 'mystery' sense or else thin, sheer silk. A shikai technique whereby Itegumo dissolves into a mist or fog, which covers a large area including Isane's location. Visibility is significantly reduced for both Isane and anyone else in the fog—but within the veil, Itegumo's _Mōshikaku_ is expanded to include tactility; any motion stirs the fog, and that information is conveyed to Isane, who can then cause the cloud to condense around whatever she likes, freezing on contact and significantly impeding her opponents.

 _Kazeshini_ – 風死 – "Wind of Death." Hisagi's zanpakutō. When released, it looks kind of like two kusarigama, except each of them have two blades, with the edges facing the opposite directions. The poles are also longer than a traditional kusarigama, and both of them are attached to one another with the same chain, so neither has the weighted ball. The chain is extendable, allowing for a lot of range. The release command is _kare_ (刈れ), the imperative of "to reap."

 _Sakanade_ – 逆撫 – This has a lot of interesting readings, actually. The Bleach wiki goes with "Counterstroke," but they can also be read as "Inverted Stroke" or even something like "Rub the Wrong Way," which is amusingly fitting for Shinji, whose zanpakutō it is. When spun, it creates a pink mist. Anyone who inhales it is subject to a perceptual illusion—that the world has become inverted, more or less. Up/down, left/right, forward/backward are all swapped, but so is vision itself and the direction of attacks. The release command is _taorero_ (倒れろ), the imperative of "to collapse."

 _Takaoni_ – 嶄鬼 – "Mountain Demon." One of Kyōraku's shikai techniques. A "game," wherein the person at higher altitude wins and the person at lower altitude loses.

 _Suzumebachi_ – 雀蜂 – "Hornet." Suì-Fēng's zanpakutō. It's a gauntlet weapon with a bladed "stinger" on the middle finger. Notable for its _Nigeki Kessatsu_ (弐撃決殺) "Death in Two Steps" technique, wherein Suì-Fēng can outright kill weaker opponents just by touching them twice in the same place. Its release command is _jenteki shakusetsu_ (尽敵螫殺), "sting all enemies to death."

 _Jakuhō Raikōben_ – 雀蜂雷公鞭 – "Hornet Thunder Whip." Suì-Fēng's bankai. It's basically a shoulder-mounted missile launcher. It's got some seriously impressive attack power, but it sucks up so much reiatsu that Suì-Fēng's normal limit for using it is one missile every three days.

 _Ginjōtan_ – 銀条反 – "Stripe of Inverted Silver." A metal-woven fabric sash heavy enough to impede movement. Suì-Fēng uses it as a training aid, and, more importantly, to anchor herself down when using bankai, so as to be able to overcome the massive recoil.

 _Gonryōmaru_ – 厳霊丸 – "Stern Spirit." Sasakibe's zanpakutō. It's a lightning-element kidō-type; the shikai is a rapier. The release command is _ugate_ (穿て), the imperative of "to pierce."

 _Raisho_ –雷撞 – "Lightning Stab." One of Sasakibe's shikai techniques. Channels reiatsu through Gonryōmaru, making use of its superior thrusting ability to launch a bolt of lightning in a straight line towards the opponent. Very fast, but suffers from an inability to bend the trajectory of the attack without assistance, and so is best used at medium ranges, where the sword alone won't quite do.

 _Sajō Sabaku_ – 鎖条鎖縛 – "Locking Bondage Stripes." Bakudō #63. Raising their palm up to the target, the practitioner closes their hand into a fist and calls forth yellow energy. It takes a form of very thick rope, which binds the upper body of the target.

* * *

So that's a thing that I did. Are you feeling the danger yet? :)


	23. Chapter Twenty-Three: Chrysalis

.

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Twenty-Three: Chrysalis

* * *

"It… it can't be." Isane shuddered—fear rose into her throat, tight and choking.

It was impossible to mistake that the Sōtaichō's reiatsu was gone from the field. She might not be the strongest fighter or anything, but she knew how to sense reiatsu. Even just flickers of it. But Aizen was here, and that made it harder, so maybe—

Beneath her hands, Ukitake tried to sit up. The expression on his face was stricken; Isane was surprised he was conscious at all. His condition had all the hallmarks of a flare-up of his lung disease. Perhaps he'd lost and then regained consciousness in the time it had taken her to get to him.

"Sensei," he murmured. His voice cracked over the word, raw and soft.

Isane didn't think she was imagining the note of utter disbelief in it, either. She supposed… he had more reason to disbelieve than anyone. She and most of the people in the Gotei 13 only knew the Sōtaichō as a seemingly-immovable figure of dignity and authority. A fixture in the arrangement of things. A star around which many planets orbited. But Ukitake knew him as much more than that.

In the same way Isane couldn't even conceive of something that could do _her_ captain in, she supposed it was a nightmare made real for him right now.

Which meant, somehow, _she_ had to be the one who kept it together. Carefully, she placed a hand on Ukitake's shoulder; she pressed just firmly enough for him to get the point. "Please, sir," she said quietly, trying to keep her voice steady and firm. "I need you to remain still so I can heal you."

Besides the bleeding in his lungs, he was heavily burned in more than one place; those would be quite difficult to contend with, even on their own.

He laid back slowly, exhaling with a wet sound. She resisted the urge to frown. Ukitake fixed his eyes on the sky above them, apparently sinking into his own thoughts. She imagined he must have too many of them, right now. But that was the kind of thing no healer could fix—she had to focus on his physical injuries.

The doubting part of her wondered how much that would be worth, if Aizen had brought some power to bear that could kill the Sōtaichō. But they couldn't afford to be defeatist. She swallowed past the lump in her dry throat, and went back to work.

* * *

Coyote didn't really understand why neither of these shinigami were using their bankai. Weren't those supposed to be the strongest weapons in their arsenal? It seemed like if there were ever a time to use something like that, this would be it.

Still… maybe they didn't have the kinds of bankai that were useful in a situation like this. He really didn't have any choice but to trust them to do the strategically smart thing.

There was a moment where Kyōraku faltered; the same moment that massive reiatsu disappeared form the field. But his expression moved from utter shock and disbelief back into the vaguely-pleasant half-smile within half a second. If anything, his eyes darkened, but there was nothing else.

Coyote supposed that was how you could tell an old soldier from a young one.

"White."

Right. So that meant only white spots would take damage. He had a very basic rundown of the "games" Kyōraku's sword could play. The other shinigami—if that was the right word—didn't, but the only white _he_ was wearing was his Hollow mask, so that probably didn't matter much.

Bringing both guns forward, he fired. " _Cero Metralleta_."

The barrage burst forward, encompassing a wide area—but he didn't really count on the fact that any of them would hit. This was Aizen, after all. Coyote still had a hard time believing this wasn't an exercise in futility. Still… they weren't dead yet.

The dark blue flashes faded away; Aizen stood unharmed inside a barrier of some kind. Kyōraku appeared behind it, bringing his sword down on it. The barrier cracked with a glasslike sound; chunks of it fell away before Aizen abandoned it entirely, moving as if to attack Kyōraku.

The masked shinigami intervened; for the moment at least, the fact that he was steadily bleeding out didn't seem to bother him much. Actually, it looked to be healing up a bit—maybe that mask came with some version of high-speed regeneration?

The swing met Kyoka Suigetsu; they clashed and pulled apart. Kyōraku's reiatsu disappeared—it seemed he'd decided to move on to part two of the plan. Coyote pulled in a deep, slow breath through his nose. He could feel himself starting to perspire; a thin sheen of cold sweat was forming underneath his clothes. That and the cottony feeling in his mouth were extremely familiar.

Every Hollow was acquainted with fear.

But now he had a reason to push back against it, and he did. " _Colmillo._ "

The reiatsu-composed guns in his hands shifted, extending outwards and reshaping until they were swords, instead. He'd never thought of his abilities as particularly impressive, but they were versatile, he supposed.

 _Hey. I'm plenty impressive, thank you very much! Now quit thinking about stupid stuff and go get 'em!_

Lilynette, as ever, was unhelpful.

With a sigh, Starrk stepped into _sonído._ All he had to do was make Aizen's feet touch something solid. He could do that.

Maybe.

His first stroke was met with Kyoka Suigetsu; Coyote bore down to try and keep Aizen in place long enough to get him with the second.

Aizen extended the index finger of his free hand, pointing it directly for Coyote's chest. Shit.

His hand shifted, the palm thrusting forward. " _Hadō #33: Sōkatsui_." Blue fire erupted at point-blank range.

Coyote disengaged, throwing his whole body to the side. From the corner of his eye, he saw the man in the Hollow mask descending from above, swinging his zanpakutō in both hands. Gritting his teeth, he shifted one of his swords back into its gun-shape.

" _Soplo._ " It solidified into the new form, and Coyote fired several blasts in quick succession.

The first rebounded off a kidō shield, but the next three broke it, and Aizen stepped away, letting himself lose a little altitude to gain distance.

That was the way of it for several long, exhausting minutes. Gradually, they drove Aizen further and further towards the ground. He appeared unconcerned by this—Coyote didn't delude himself into thinking he didn't _notice_. But his expression never changed, no matter how much pressure they put on him. And it _was_ pressure; or he believed it was.

But the unruffled half-smile on Aizen's face did not falter; an air of expectancy hung over the fight. Even as Coyote and his masked ally threw more and more of their power into the match, it was almost as though Aizen was waiting for something in particular. It was probably better not to let him get it.

Finally— _finally_ , his feet touched the ground. Coyote couldn't let his relief show. Instead, he kept up the attack, firing several hundred _ceros_ from the barrel of the gun in his left hand. Pushing more energy into the sword in his right, he prepared to charge.

It happened in an instant.

Aizen was raising Kyoka Suigetsu to block again when a heavy, curved blade erupted from the center of his chest. Dark red, reflective and macabre, coated the silver edge of the black sword; a drop of it splashed onto the ground under them.

Kyōraku had emerged halfway from Aizen's shadow; without even the faintest hint of mercy, he swung his lighter blade for the place Aizen's collar lay on his neck. That was right—the color was still white.

"Destroy the orb," Coyote said urgently. He'd seen what became of Ichimaru when he'd tried to simply take it away. There was no guarantee that even a fatal wound would actually kill Aizen at this point. They had to neutralize the Hōgyoku first.

A massive swell of reiatsu followed; Kyōraku's sword started to glow with it. He twisted the blade even as his other bit deep into the juncture of Aizen's shoulder and neck. Coyote could hear a high-pitched, grating screech as the zanpakutō scraped against the sphere lodged in his chest.

For the first time in the entirety of the fight, Aizen looked genuinely surprised. Almost hastily, he gathered his reiatsu to himself and pushed outwards with it, throwing all three of his opponents back. A bright flash of light obscured him for several seconds. Coyote landed hard on his feet, the impact jarring his knees, and pulled in the breath he'd lost.

This wasn't good—Aizen's reiatsu was spiking. He'd never felt this much of it before, pressing up against his sense for it the same way thick, roiling smoke pressed up against his sense of smell. Not only heavy, but choking. Overwhelming enough to shut out nearly everything else. He felt a droplet of sweat slide down his back, and swallowed.

The light faded; what stood before them hardly looked like Aizen at all. He was… encased, from head to toe, in white. His entire face had been smoothed over—he didn't even look like he had a mouth, though Coyote could still see his eyes. Those had turned black from sclera to pupil, with nothing to differentiate the parts.

What _was_ this? What was _he_?

Whatever he was, the injuries Kyōraku had inflicted on him were gone now, like he'd never been stabbed or half-beheaded at all.

"Intriguing," Aizen said. His voice was somehow clear despite the lack of a visible mouth. "I would never have expected that the likes of you could force the Hōgyoku to evolve. You have my thanks."

 _Oh, fuck. We're in trouble, aren't we?_

 _Yeah, Lilynette,_ Coyote replied. _We are._

* * *

"Are you sure this is going to work?" Yoruichi hefted the armor plating on her arms. Leave it to Kisuke to devise a solution like this when she'd complained about hierro.

He fluttered his fan in front of his face, stirring the ends of his shaggy hair. It looked like he hadn't trimmed it in over a year. "Sure? I'm never _sure_ , Yoruichi. But I'm _pretty_ sure, yeah."

She rolled her eyes. This man—no one frustrated her like this idiot did. Fortunately, she knew him well enough to trust him anyway. Adjusting the straps holding the armor on so that it fit more snugly, she tapped her toes on the ground. It was basically a white shell, but there was enough movement in the joints that it should be almost as good as fighting in her old uniform. He'd conspicuously left the back uncovered; probably with the same thing in mind. The rest of her was encased, though—it fit close, but not so close it'd be useless.

"What about you?" she asked, flicking her eyes up and down. He very evidently hadn't bothered to wear anything but his usual green-and-white. Including the damn hat, of course.

"Don't worry about me," he replied, all easy, light words. She could hear the smile in them, even though the fan obscured the lower half of his face.

Yoruichi's tongue curled in her mouth. Kisuke was this blasé in two types of situation: ones where he'd already won, and ones where he was absolutely doubting that he even could. She had serious trouble believing this was the former, even for him.

"Yoruichi." He caught her eyes with his, snapping his fan closed and tucking it back up his sleeve.

He wore a tilted smirk as usual, but the sharp edge to it softened just a little bit. "Trust me," he said. But it was a request, not a demand. No matter how authoritative he got with other people, he never _told_ her what to do. He asked.

And most of the time, she acquiesced. Yoruichi jerked her chin, pulling in a deep breath. "Yeah, all right. Let's do this."

"Whenever you're ready." Tessai glanced from one to the other, his mouth set in a grim line. Yoruichi knew he wanted to go as well—the three of them had always done the important things together. But containing Aizen and his damage to this area was what _all_ of them were ultimately trying to do, and this barrier was the last line of defense.

"Let's do it," she replied.

Tessai nodded, parting the barrier for them to enter. In step with Kisuke, Yoruichi entered.

Immediately, her senses were assaulted by dozens of reiatsu signatures of varying strength. Some of them were so familiar she didn't even have to seek them out—Suì-Fēng was with Hachigen, both of them heavily injured but alive, it felt like. Ukitake and Kyōraku were certainly alive as well. She'd felt the Sōtaichō's reiatsu go out even through the barrier, but she also couldn't pick out some of the others, ones less familiar. The sheer heft of _Aizen's_ spiritual pressure made it difficult to see anything she wasn't already looking for.

There weren't too many Arrancar left, but considering what they'd managed to do to the Gotei and Visored presence here… it might not matter.

Yoruichi pursed her lips, adjusting the cloak over her shoulders; she couldn't feel the fabric through the clawed gauntlets encasing her hands. Kisuke wore one just like it—they should be able to get the drop on Aizen this way. She figured it might be their only chance. But then… all she knew of Kisuke's plans was that they involved time, and something from Hell.

And most likely Uryū as well, though she wasn't sure how.

He glanced at her from the corner of his eye, expectant. She nodded, and they stepped into _shunpō_.

* * *

Sōsuke flicked his fingers.

The shockwave caught Shinji hard in the stomach, throwing him through the nearest building with a massive crash. Beneath the chrysalis encasing his mouth, he smiled.

He'd always suspected the Hōgyoku would be capable of something on this scale. But the reality of it—the weightiness of its presence in his mind, slowly blurring and blending at the edges with what he'd been before… it was utterly sublime.

One of Kyōraku's swords came in from overhead; Sōsuke raised an arm and caught it in his hand. Gripping it tightly, he pulled it and its wielder over his shoulder and threw them. Kyōraku reoriented in the air faster than Shinji had; there was no momentous crash this time.

"Really… attacking from behind, hiding in shadows… what interesting tactics you have, Kyōraku-taichō."

Rolling his shoulders under his garish kimono, the man half-smiled. It was an utterly mirthless gesture. "Well, Sōsuke-san, we're all villains here. I just thought I'd play my part. _Bushōgoma._ "

He spun, creating a powerful gust of wind with his outstretched blades. Sōsuke simply let it hit him. When the barrage of blue _ceros_ flew in from his right, he let those hit him, too. They weren't capable of putting even a crack in his chrysalis.

" _Bakudō #61: Rikujōkōrō._ "

Six bright beams of light slammed into Sōsuke's midsection, temporarily locking him in place.

" _Bakudō #79: Kuyō Shibari_."

He actually lost the feeling in his extremities for a moment when the black discs formed, each siphoning the reiatsu around itself. Not that such a thing had hope of containing all of it.

" _Hadō_ _#91: Senjū Kōten Taihō_."

Interesting.

Sōsuke elected not to dodge the kidō, letting it hit him. The blast was impressive, he had to admit. Had he not been encased in this chrysalis, had he not been merged with the Hōgyoku to such a degree, a combination like that, executed swiftly and without warning, might well have felled him. There was considerable power in it—more than he remembered Kisuke Urahara to be capable of.

Oh, how much had changed.

Flaring his reiatsu, Sōsuke broke the bakudō spells still holding him in place, and turned to face his new adversary. The opportunity to speak, however, was temporarily denied him.

A flicker of reiatsu alerted him to the incoming attack; Sōsuke sidestepped away from Yoruichi Shihōin as she drove towards him with a kidō-enclosed fist. He wondered for a moment what the gauntlet on her arm was for. Perhaps just this situation—if anyone could be expected to predict him, it was Urahara.

She surprised him by shifting into a kick—the greaves on her feet were made of the same material. The blow connected with his knee—and there was indeed a hairline fracture in the chrysalis now. Perfect.

The Hōgyoku's power stirred, the line between it and him becoming even more difficult to discern.

Oh, excellent. If anyone could push him to the final stage of being, could push him to the pinnacle of adaptation—surely, _surely_ they could. There was hardly a stronger group of foes he could possibly face than those arrayed before him now.

Once he had bypassed them, nothing the Zero Division could throw at him would even _matter._

* * *

"Well, Aizen-san… it seems that merging with the Hōgyoku has really made you let your guard down."

The newcomers were familiar from data Coyote had been shown—these were two of the three ex-shinigami living in Karakura Town. Aizen seemed to be pretty fixated on the speaker—Kisuke Urahara. That was his name. If Coyote didn't know any better, he'd say this whole thing had almost been like… like what was supposed to be the final match in a longstanding rivalry.

Maybe that had influenced the _way_ it was happening, at least.

"Behind you, Kisuke!" the woman—Yoruichi Shihōin—shouted.

Aizen did indeed appear right there; Coyote fired a _cero_ , knowing it would hardly be a deterrent if a spell like that wasn't. Aizen caught the projectile, crushing it in his palm.

"You're right," Aizen said, arching a brow. "I will let my guard down. For there is no longer any need to be on guard. I can feel it—my body has subjugated the Hōgyoku. And now the entirety of my abilities, once unsurpassed in all of Soul Society, are beginning the climb to even greater heights."

"Yer not very humble, are ya, Sōsuke?" The blond man's mask had disappeared—Coyote could only suppose that there must be a time limit on the ability. Without it, he seemed to be in pretty bad shape.

Then again… none of them were doing that well, considering what they were stacked up against here.

It was pretty clear that Aizen wasn't even talking to them anymore—everything he said was directed at Urahara.

"Even kidō in the nineties no longer warrant avoidance!" It was also the most agitated Coyote had ever seen him—what the hell was that orb thing _doing_ to him? Or was this just what he looked like when things got serious?

He'd spent so long in this man's company, under his command—and really, he didn't know anything about him at all. Coyote had no doubt that it was on purpose; the asymmetry was the very same one Aizen enforced with all of his underlings. And that was all they'd ever been.

No.

'Underlings' was still too personal a word. Too human a word.

They'd been pieces, and nothing more.

"You've misunderstood," Urahara said; for a strange moment, Coyote almost thought he was answering _him_ —confirming his observation. But of course he was talking to Aizen. "When I said that you let your guard down, I wasn't referring to you not avoiding kidō." He tipped his head to the side, slanting his body language. "In the past, you'd never have come into physical contact with me twice without any kind of plan." He sounded almost… disappointed?

Kyōraku had disappeared again. Coyote wondered if Aizen had even bothered to notice. That was the strangest part—as far as he could tell, it wasn't Aizen's reiatsu or even his zanpakutō that made him so terrifying. It was the way he _knew_ so much. Things he shouldn't know. And the way he could bring that information to bear before most people could even process it.

Why abandon that now? He must be playing at some kind of longer game.

"Shit," that was Shihōin. "Incoming!"

Anzparrejar seemed to just spontaneously appear beside Aizen; blood dripped lazily from the sword he'd laid over his shoulders. He must have downed his other opponents already. Coyote frowned; another problem they really didn't need right now.

"Someone's got to cover him," he said, jerking his head at the masked Espada.

Shihōin and Urahara exchanged a look. "I've got it," she said.

"I'll help." Both of them turned to Coyote for a moment. "I'm not much use here, but I might be there."

As far as he knew, Anzparrejar couldn't just _catch_ a _cero_.

Shihōin nodded. "Then let's go." Something resembling electricity crackled to life around her shoulders and arms, and she flashed forward with impressive speed. Her fist connected solidly with Anzparrejar's chest, sending him flying.

Coyote fell in half a step behind and a few feet below as she charged after him.

His angle let him see the other Espada's attempt at retaliation; Coyote launched himself forward with _sonído_ in just enough time to get in front of her. He wasn't sure how good her armor was, but he knew his own hierro.

Or at least, he'd thought he did.

Anzparrejar seemed to simply _materialize_ in front of him; Coyote reacted just as quickly, bringing up the sword in his right hand to block. The cleaver the other Arrancar wielded screeched against his _colmillo_ ; he dismissed the gun in his left and used the arm to brace the upper half of his blade. Being composed of his own reiatsu, it didn't cut him.

He swore the contours of Anzparrejar's mask shifted slightly, hinting at a change in the expression. Without warning, the claws tipping his fingers extended, piercing Coyote's hierro when the pressure grew too much for it to withstand.

" _Transcripción_."

What followed was a sensation he didn't quite have the words to describe—it was as though there was suddenly a third presence in his inner world, one that called up his memories and thoughts at its whim, shuffling through them like a curious, dispassionate archivist. Foreign eyes replayed his every thought and feeling, casting them aside and probing deeper to find what it sought. Pain split his head, his chest, his… It felt like something deeper than his physical body was being torn at—mauled.

The claws ripped free of his chest—Shihōin had hit Anzparrejar hard enough to dislodge them. He flashed backwards, retracting his claws and curling his fingers into his palm.

"I know," he said lowly, in a hissing rasp. "I know what you cannot cut, Primera Espada."

"The hell?" Shihōin glanced at him, as though she expected him to understand what that meant.

But he didn't. Not at first.

Anzparrejar leveled the blade he wielded out to his side, straight in a line with his arm. The ends of his fingers dripped blood onto the hilt's spare wrapping. " _Musaboro, Piraña._ "

His reiatsu level spiked—every resurrección did that. The excess gathered around he and the sword both; it was a peculiar, red-tinged black. Slowly, it detached, like molasses pouring away to the side, and reformed beside him. The mass shrank until it was considerably shorter than Anzparrejar himself, then reformed into a humanoid shape.

Coyote's eyes rounded in surprise. When the release finished, what was standing next to the other Espada was—

"Yuzu?"

The resemblance was perfect, down to the shape of the zanpakutō and the way she propped it back against her shoulder to leave her hands free. It even _felt_ like her; the reiatsu signature was identical to the one he remembered.

Remembered.

That was it—that had been the point of sifting through his mind earlier. To gain this information. To be able to… replicate her.

 _I know what you cannot cut._

He wasn't wrong.

* * *

Kisuke grimaced when Shinji fell out of the sky.

It was certainly a good thing that Aizen was far too arrogant to do what Kisuke would have done and follow his opponent to the ground to finish him off. It meant Shinji might actually survive, with a little help.

Unfortunately, he personally had bigger things to deal with right now than seeing to that. Aizen was fighting, if not completely seriously, at least _actively_ now. That meant he had to pay attention. He'd already initiated the plan, but it wouldn't do much good if he couldn't trigger his own trap. At best guess, he still had a while to go before reinforcement would arrive, and with Yoruichi tied up with _that one_ , he had little choice but to enter the fray himself.

" _Kageoni._ "

Of course, he wasn't entirely alone.

Aizen narrowly avoided Kyōraku's blow, twisting to deliver a retributive slash with Kyoka Suigetsu. Kyōraku lost his hat and gained a cut on his cheek, but it was far from the beheading Aizen had doubtless intended for it to be. That was good—this would never be a knock-down fight on their end. Fine. The important part was that it never quite became a runaway victory for Aizen, either.

Kisuke could win a war of attrition.

" _Nake, Benihime._ " With a slash, he flung a swath of crimson reiatsu at Aizen, murmuring a kidō under his breath and flashing forward.

When his adversary cut through the energy attack with his own reiatsu, Kisuke deployed the kidō; one of several of his own construction. They activated immediately—a response to the amount of reiatsu Aizen was exuding just standing there. Kisuke was sure that doing that for show had considerable tactical advantages, but it really was just asking to be exploited, even if only temporarily.

Aizen's black eyes widened; he seemed quite surprised at the doubtlessly-nasty burning sensation he was experiencing right then. "What are these?"

Kisuke tugged at the brim of his hat. "I blocked off the reiatsu vents in your wrists." He half-smiled, narrowing his eyes. "This will be unpleasant for you."

On cue, Aizen's body erupted, a pillar of nearly-colorless reiatsu extending to the ground and just as high above. Kisuke sighed, descending to touch down on the ground. Kyōraku wasn't more than a step behind.

"That's not gonna do him in, is it?" he asked, shucking his pink kimono. He pulled the pins out of his ponytail and tucked them carefully against it; straightening, he rolled his shoulders, brushing a few rivulets of blood off his cut cheek with his thumb.

"It'd be lovely if something like that was the end of this," Kisuke agreed wryly. "Since that would mean he was just an _ordinary_ monster."

Kyōraku's breath left his nose a little too fast—it was almost, but not quite, a snort. His expression lacked all humor, however. "Just our luck, right?"

"Never trust anything to it." Kisuke drew a length of chain out from his sleeve, tossing it to Kyōraku. "Care to help me out?"

The captain bobbed his head obligingly. "Certainly. I have to ask, though, Kisuke-san: what exactly are we hoping to achieve here?" He cocked his head to the side; there was no mistaking the seriousness of the question.

Kisuke arched an eyebrow; it disappeared under his fringe. "Terminal velocity."

* * *

 _Term Dictionary:_

 _Cero Metralleta_ – 無限装弾虚閃 – The kanji are "Infinite Ammunition Hollow Flash" and the Spanish is roughly "Machine Gun Zero." Starrk's cero barrage technique. He can change the direction of them when they're in motion, making them tough to avoid.

 _Colmillo_ – 力牙 – The kanji (which I gave it) are "Energy Fang." The Spanish is just "Fang." An energy manipulation technique of Starrk's resurrección that allows him to form blades with it. The shape and number is variable, but he usually only bothers with one or two. I've had to try and unify Starrk's release a little, since it just seemed to be a random collection of stuff in canon. So, for headcanon/AU purposes, he has a suite of abilities that involve manipulating raw reiatsu into different forms. Swords are one of them.

 _Soplo_ – 力吐息 – The kanji approximately come out to "Powerful White Breath." The Spanish is "Breath/Puff/Gust." AU!Starrk's way of generating his guns. His resurrección has variable shape even in canon, so I just gave him a named technique for forming his reiatsu into the cero-blasting-hand-canons. He can switch back and forth between them and the other forms without difficulty—as he does in this chapter.

 _Bushōgoma_ – 不精独楽 – "Lazy Spinning Top." One of Kyōraku's shikai techniques. By rotating himself with both blades facing in opposite directions, he creates large wind blades which fire toward an opponent.

 _Senjū Kōten Taihō_ – 千手皎天汰炮 – "Thousand-Hand Bright Heaven Culling-Sear." Hadō #91. Generating ten pink energy points around themselves, the practitioner fires them all at their target, resulting in an exceedingly devastating explosion.

 _Transcripción_ – 血染筆 – The kanji are "Blood Writing." The Spanish is "Transcription." One of Anzparrejar's techniques, which if you know your canon, probably gives away something pretty important about what, exactly, he is. By physically piercing an opponent with his extendable claws, Anzparrejar gains limited access to their memories and emotions, enabling him to discover what is dearest to that person—and therefore what they could not bear to harm.

 _Piraña_ – 白切歯肉食魚 – The kanji are "White-Toothed Carnivorous Fish." The Spanish is "Piranha." Anzparrejar's resurrección. Using data gathered by _transcripción_ , Anzparrejar splits his reiatsu, forming part of it into a perfect replica of whatever the opponent is psychologically unable to fight. The replica gains the weapons, manner of speech, and so on of the person in the victim's memory, but cannot use the same techniques, unless Anzparrejar knows them himself. They can, however, use any technique that he knows, such as sonído. The release command is _musaboro_ (貪ろ), the imperative of "to devour greedily." It also means "to covet," and "to desire insatiably."

 _Kageoni_ – 影鬼 – "Shadow Demon." One of Kyōraku's shikai techniques. The game it is linked to is one where whoever gets their shadow stepped on loses. He seems to have a variety of shadow-based powers to go with, however, including being able to hide himself in another person's shadow and generate shadow clones, etc.

* * *

So… you probably have at least some idea what's up with Anzparrejar now, if you didn't already. Surprise-not-surprise, I guess. But if you've sorta forgotten the relevant bits of canon, there's a more complete IC explanation upcoming, so don't worry!


	24. Chapter Twenty-Four: Synergy

_._

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Twenty-Four: Synergy

* * *

Yoruichi's fist connected with the Arrancar's stomach; not a second later, she pushed the lightning-element reiatsu crackling around her knuckles forward. That combination—heavy physical impact followed quickly by heavier kidō impact—was something she'd refined to break through any Hollow hide she'd ever come across.

Unfortunately, the only thing crunching right now was the armor plating over her knuckles.

Shit.

This… _Nula Espada_ , the other one had called him—he wasn't a joke. Flashing away before he could decapitate her, she drove a knee into the Yuzu-replica, knocking her away from her temporary ally. Why it was that the release had taken this particular form wasn't completely clear, but she had a working hypothesis. He was certainly having a hard time fighting her. The spear-tip on the copy of Hasuhime had opened up a deep welt in his chest, from the shoulder on one side to the hip on the other; bright red seeped into his white uniform.

This guy must be a lot more sentimental than he looked.

"It's not her," Yoruichi said, making a grab for the fake Kurosaki twin. Unfortunately, she ducked out of the way; Yoruichi had to spring back to keep away from the same polearm. But then the other one was back—the actual Anzparrejar or whatever his name was supposed to be. He was deliberately forcing her to engage with him so that the other one could pressure her ally.

"I know," he replied, but knowing and acting on the knowledge were clearly different. He still couldn't seem to bring himself to do much more than fire potshot ceros at the spitting image of Yuzu. His movements were getting slower; there was no telling how much longer he'd last.

Yoruichi ducked a swipe of Anzparrejar's cleaver, surging to her feet and aiming an uppercut for his jaw. Bending backwards away from it, he caught her in the temple with the wrapped handle of his zanpakutō. For a moment, she saw stars and not much else. His follow-up knocked the wind out of her; she felt a rib crack under the pressure of the punch. Only the armor saved her from losing her head—the high collar of it cracked off when he hit it with the sword.

She moved with the blow, throwing herself to the side and raising a hand to her neck. It came back bloody—there was a shallow cut there that could have been a whole lot worse. The armor wasn't exactly _standing up_ to the abuse, but considering how poorly her skin would do, she was lucky to have it at all.

To her right, her ally caught the fake Yuzu's ankle and threw her—definitely not the most damaging thing he could have done with positioning like that, but it was something. That freed him for a moment; he fired a massive barrage of _ceros_ nearly point-blank for Anzparrejar.

When the masked Arrancar emerged, it was with several new holes in his cloak, and one smoking burn on his shoulder. The gunman had paid for it, though; Yoruichi could tell he was getting tired. Who knew how long he'd been at Aizen before this—and _that_ many full-power _ceros_ was no small feat.

She wasn't honestly sure how much longer they'd last at this. If need be, she had a few more things she could try, but… she had to admit the prospect of a two-on-one fight was not a happy one, even for her.

Yoruichi gritted her teeth. Happy or not, this was necessary.

* * *

"Are you prepared?"

Yuzu pursed her lips, glancing over her shoulder at the others. Unohana-taichō was just finishing Uryū's full reiatsu restoration. There probably wasn't any more they could do—there was almost certainly no more time they could afford to spend here.

She let her breath go in a sigh. "We'll have to be," she replied softly.

He seemed to contemplate that for a moment; eventually he nodded. "Then this will likely be the last time you see me," he said simply.

Yuzu blinked; Ulquiorra disappeared and then appeared again in her field of vision. "What makes you say that?" She knew he was unlikely to be optimistic about their chances, but this didn't quite seem to have the tenor of mere cynicism.

His expression remained flat as ever, as did the tone in his voice. "You are about to leave Hueco Mundo. I am not. There is no reason for you to return to Las Noches after this."

Yuzu felt her mouth pull to one side at the same time as her brow knit. "No reason? Wouldn't seeing you be a reason?" Or Starrk, or even Grimmjow? Assuming the latter would be interested in the first place. It was kind of hard to tell with any of them.

It was equally difficult to tell if Ulquiorra had nothing to say or she'd actually succeeded in rendering him speechless. From the fact that his lips parted and no sound came out, she tentatively inferred the second. Yuzu supposed it _was_ a little strange; she hadn't exactly planned to say it, but now that she had, it made complete sense to her. It was hardly as though they'd be welcome in Soul Society, no matter how vehemently she vouched for them. No doubt she'd be dismissed as a traumatized victim clinging to any shred of kindness she could read into an action.

But those were thoughts for later.

"We can open gargantas now," she added, more firmly this time. "I see no reason not to make use of that."

Ulquiorra pushed a breath out of his nose; it sounded suspiciously like a sigh. "As you wish," he replied at last. "But do not open any outside of Las Noches. Knowing a few Arrancar does not make you welcome in Hueco Mundo."

She smiled, dipping her chin. "I know. And I won't. But I _will_ be back. You can count on it."

"I suppose that I can."

* * *

Karin stepped out of the garganta, and into a warzone. Literally.

The first thing she noticed was that she couldn't feel as many reiatsus as she probably should—that was bad news.

The second thing she noticed was that Aizen's reiatsu, like a giant, stinky cloud of the stuff, was fucking everywhere and practically thick enough to choke on. Ugh.

She might have noticed other things, except Yuzu got her attention with a gasp. It didn't take too long to figure out what that was about—because apparently there was _another Yuzu_ on the field, and she was beating the tar out of some guy Karin had never seen before. Yoruichi was there too, and—

"Him." Hitsugaya finished her thought out loud. That might have been weird, except really she figured he was just as likely to be thinking it as she was.

Because fighting on not-Yuzu's side was that fucker who'd almost killed them both more than a month ago.

"Dibs," she said quickly, drawing Hisaku. Really the chance she could do shit against Aizen without specific directions was stupid-low. She wouldn't have minded fighting those odds if it came to that, but why make things impossible when there was another way forward?

 _See. I can learn things._

"We should all go." The old man sounded unusually serious for some reason, like his voice was tied down with a lead weight. Or—whatever. Metaphors weren't her strong suit.

If she, him, and Yuzu did that, it left them with Kuchiki-taichō, Hitsugaya, and Uryū to reinforce the fight against Aizen, but Yoruichi could go there too if they took over. Karin wasn't really sure if that was a fair trade or not, but it was what they were going with, because no one was disagreeing.

Hitsugaya looked like he was there to murder someone. Karin didn't have to think too hard about who.

"Hey," she said, drawing his angry glare for a moment. "Don't be a dumbass. You look like you're about to be a dumbass."

"You're one to talk," he sniped back; but she _did_ notice him force his shoulders to relax a little, so whatever.

They split with no more fanfare; all of them released their zanpakutō as they flashed away. Karin felt the familiar warmth of Hisaku under her hands and let it focus her. She wasn't at full power—not even healing like Captain Unohana's could bring a person from _just fought a goddamn Arrancar_ to _full steam ahead_ in less than an hour. But she had her reiatsu back, at least, and she was sore instead of busted up. It'd do.

 _Here goes nothing._

* * *

This chain was quite impressive. Even in this state, it—and the strength of the two holding it—had effectively locked him in place. Urahara's section had caught him around the ankle and lifted him onto one foot; in the intervening time, Kyōraku had looped the other section around his neck.

Even Sōsuke still protected that part of his body. It was an instinct he may have no longer needed, but it was powerful all the same. His left hand pushed back against the chain from inside the loop, keeping it from strangling him. They both pulled; he went mostly horizontal.

When he felt the garganta open over the field, he went in search of Momo's reiatsu, expecting to find her either unconscious or close enough. Strangely, it seemed she was awake, though weak. There was nothing stopping him from using her image anyway, of course—he could render her invisible and inaudible to everyone around her and do whatever he wished with her likeness. Or twist her, so that she appeared to be him, sneering down at a field full of enemies who wouldn't think twice before running him through.

The possibilities were nearly endless.

But… illusions were for those who had need to hide something. Cover a weakness, disguise a flaw. Subtlety was for those who could not win with outright power. Once, he could not have stood against the entirety of the Gotei 13 by himself. And so once, he too had needed illusions.

The Hōgyoku pressed against his consciousness, its power seeping into his mind, washing over the surface of his thoughts like an ocean wave and sinking like a long, slow rain into the soil. It was him, now, and he was it.

What need had he for illusions, when such power responded so well to his every wish?

Sōsuke dropped Kyoka Suigetsu, using his now-free hand to grab the chain near his head. With force, he contracted his whole body, yanking his knee in towards his chest and his arms both to his abdomen. The sudden application of strength caught both his opponents off guard; they lurched forwards.

" _Hadō_ _#90: Kurohitsugi_." He aimed the kidō at Kyōraku, enclosing him in a prism of opaque black reiatsu. Swords and spears, composed of the same, hovered around the outside, then pierced the enclosure as one. Interesting; he was up nearly the spell's full power, even without incantation.

On his other side, Kisuke Urahara adjusted his hat, his released zanpakutō tucked under one elbow. Before either of them could speak, their so-called reinforcements arrived.

A swirl of tiny blades surged in from the right, a volley of ice-daggers from the left. Sōsuke repulsed them all with a _dankū_. The _kurohitsugi_ dispersed—somehow, Kyōraku was still standing. Large slash wounds oozed blood from his shoulders and torso. The white haori of his division bore dark red patches at irregular intervals accordingly.

But he was alive. Well, well.

The two interlopers who'd tried to attack him and the one who hadn't landed on the ground. He was surrounded. How quaint.

"Aizen," his name was pure venom in the youngest captain's mouth, of course.

If Sōsuke had been able to, he would have smirked at him, just to make it all that much worse. Of course, Kuchiki wore no expression at all. The other, however…

"It has been some time, Quincy child."

 _Impossible_ had little meaning for Sōsuke. Even less now than it had once had. And yet, this boy was impossible—a fundamental contradiction in the laws of the universe. Empty and full at the same time. Naturally so. How peculiar.

Clearly, he'd realized this himself, on some level—or Urahara had realized it for him—because he was wielding a shinigami's zanpakutō and wearing a shinigami's shihakushō. And why not? Sōsuke had made sure they'd throw any weapon at him they possibly could. Even the ones they hated the most.

The boy—though that was hardly the proper word—scowled, but did not reply.

"It seems this is the last of what you have," Sōsuke mused aloud. "I think it only fair that I bring to bear the rest of _my_ resources as well, don't you?"

It didn't really matter if they agreed; the garganta overhead was opening anyway. What spilled forth from it was nothing especially impressive, at this stage: Gillians and extra Numerós; ones not chosen for any fracción and not contained within Hueco Mundo, but in the underground complexes surrounding it. None of them could hope to stand against even one of those around him. But against their fukutaichō, their already-injured allies and underlings, they would be quite formidable indeed.

"Alas, my scavengers are nothing so impressive as what you've mustered. They will do as scavengers always do—eat the weak and the dying first."

"Dammit." Little Captain Hitsugaya looked torn for several long seconds, but then he flashed away, doubtless to stem the tide and protect his bond-sister. Utterly predictable, that one.

Kuchiki did the same a moment later. The young Quincy looked like he wanted to join them, but Urahara spoke before he could.

"Not you, Uryū."

He halted, eyes flickering between the others, and then to Sōsuke himself. A moment later, Yoruichi Shihōin landed in a crouch next to Urahara.

Sōsuke smiled beneath the chrysalis. "Shall we begin again?"

* * *

Isshin faced down the masked Arrancar, Karin to his left. Yuzu was patching up the other one—apparently a friend of hers. That was fine. The truth was, he didn't want either of his daughters to see this, to know what this was. But he also knew that they needed to. That he couldn't keep it from them, much as he might want that.

They'd chosen this path when they became shinigami. It was often the path of most resistance, the path that cost you more and hurt you more than the rest would have if you'd chosen one of them instead.

Perhaps that was how it should be.

But this… this was something that needed correcting. This was a pain that must end.

"What the hell _is_ this?" Karin, as usual, was not the least bit delicate or subtle in her phrasing. She openly stared at the false Yuzu, then flicked her gaze over to the Espada. "Hey! What gives, asshole?"

The Arrancar was quiet in response. Isshin pulled a deep breath into his lungs, pushing down the unease in his heart. Now was not the time for reservations or regrets. He had been waiting for this moment for years. Suspended at a point in time he could not move past. His daughters had done a better job than he, but even they were still tethered by it, because he was. For them, for him, and for Masaki and Ichigo as well, he had to do this.

" _Moero, Engetsu._ "

* * *

Nanao could feel the pressure of a headache building behind her eyes, but she refused to remove them from the massive screen displayed in front of them. The command post had been set up in the First Division, but much of the equipment and its operators were from the Twelfth. For the moment, she, the technicians, and the Third Seats of every division save the Eleventh and Fourth were gathered in the command room itself, but it was quite likely that most of the Gotei 13 were watching some version of the same live feed.

She forced herself to remain upright and still; the expression on her face did not waver from the smooth, cold, impassive visage she permitted herself. Not even when her heart rose into her throat. Not even when she thought she was going to choke on her own breath. Not when they lost Zaraki to a sneak attack. Not when someone she'd long thought dead had appeared on the battlefield, wearing a Hollow mask. Nor when Komamura fell to a lime-green _cero_ , fired by someone she once knew. Not when Ukitake fell from the sky, trailing ribbons of blood behind him. Not when they lost the Sōtaichō and possibly Sasakibe to flames so bright she could almost feel their heat on her skin. Not even when Kyōraku-taichō was enclosed in a _kurohitsugi_ potentially strong enough to end even his life.

It was even harder to hide her relief when it did not.

But now she found herself with the need to tear her eyes away. Difficult as it was, she forced her eyelids to close and turned to her left. "Kotetsu-san. Unohana-taichō's group will be arriving in the Seireitei via garganta shortly. Inform her that her triage teams are standing by for her command… and that I have already taken the liberty of deploying the first and second Special Relief Units onto the borders of the replica Karakura Town."

They would be needed. But now—with all those Gillians on the field _and_ the leftover Arrancar—it was simply too dangerous to admit them into the area until the numbers thinned considerably. Of course Aizen would have anticipated the moment she wanted to send them in—when most of the Arrancar were dead and the others were occupied. And of course he would have made that impossible.

Kiyone nodded. "Yes ma'am." The informality of SWA meetings was one of the first casualties of this battle.

"Akon-san: can you switch the main camera back to Aizen?"

"Of course, Ise-fukutaichō."

* * *

Uryū hit the building hard; masonry and glass gave way under the impact, and still it barely slowed him down. He only managed to regain control of his motion after he struck the second in a row.

It was oddly surreal—he was knocking over what should have been an office building and a hotel at the center of his hometown. Of course, they weren't really those buildings, but the resemblance was impressive. Hooking Yorugen over a protruding pipe, he hauled himself upwards, grunting when pain spiked across his back. He hadn't broken anything; probably not even skin. But if he survived today, tomorrow would be a mess of bruises, he was certain.

Aizen hadn't pursued—no doubt one of the other three had interrupted him. Uryū wasn't sure exactly _why_ he had to be involved with this particular fight; he'd _watched_ Aizen drop his sword, and he knew it was the truth of things, because he'd never seen the shikai. So if he wasn't using his illusion powers anymore, they'd strategized wrong in Hueco Mundo and he shouldn't be necessary here.

So why the hell had Urahara made him stay?

Gathering reishi under his feet, Uryū tensed the muscles in his legs and pushed off it, launching himself forward again. Drawing a _kagegaitō_ around himself, he cloaked his reiatsu and angled around to approach the battle from a different side to the one he'd left it at. Letting go of Yorugen and allowing the guards to keep the blades hooked on his hands, he pushed reishi into the pentacle on his wrist, summoning a bow.

It was similar to Ginrei Kojaku, but the energy took a more solid form. Drawing it back, he sighted down the shaft of the arrow and released several shots in quick succession, banishing it in the next instant and swinging Yorugen back up into his grip to follow the arrows in.

Yoruichi ducked aside at the last second, her body providing a screen for the incoming attacks in a way that he had to assume was on purpose. The arrows slammed into Aizen's center mass with enough force to kick up considerable dust and blot the sky overhead. Kyōraku-taichō took the opportunity to step into a newly-formed shadow patch and disappear.

Uryū felt the odd disturbance when his captain moved between shadows, coming to rest in his. It was a strange harmonization in their abilities; Uryū immediately split his shadow into two, moving the new one slightly to the right.

When the dust cleared, he lunged forward with Yorugen in both hands. Aizen blocked the left easily with a forearm; his opposite palm caught the right-hand blade. Rather than fight the lock, Uryū retreated into his second shadow. The sudden absence of anything solid to grip threw Aizen's balance; in that moment, Kyōraku reappeared, positioned exactly behind Uryū. Slashing through his incorporeal body, he caught Aizen across the chest hard enough to leave a crack in the carapace there.

Both of them jumped away. When Aizen stepped backwards to steady his balance, Yoruichi came in from above, dropping her left leg right on top of his head in a kidō-infused kick. The armor protecting her there shattered, flaking away into a hundred or more tiny pieces. Aizen caught her ankle and tossed her.

" _Bakudō #37: Tsuriboshi_!" Uryū fired the kidō in the same direction; it webbed outwards and stuck to several still-vertical buildings grouped in a cluster.

Yoruichi hit the soft middle part of the spell with enough force that it rebounded and launched her forwards again.

"Duck." Urahara's voice came from behind him.

Uryū ducked.

" _Nake._ " The crimson blast of energy flew by over his head, hurtling into the same spot on Aizen's chest Kyōraku had gotten. The crack deepened.

Oddly, Aizen didn't seem at all concerned about this. He could have moved away from the strike, or tried to, but he hadn't. Urahara _had_ to have noticed, but he was wearing away at the spot anyway. Uryū wasn't sure what that meant, but there was little choice except to go with it.

Uryū and Kyōraku went in at the same time again, only to be thrown back by a blast of reiatsu. Aizen followed up with an actual kidō, firing a _raikōhō_ point-blank for the captain. Uryū flashed forward, stretching his arm out until his shadow fell _just_ close enough for Kyōraku to vanish into, then immediately away again when Yoruichi charged in.

His captain emerged rather than stay hidden this time; it was clear to Uryū that he'd been in this fight for considerably longer than the others, at least if his injuries were anything to go by. But while he complained about every little cut or hit in a sparring match, he seemed quite capable of ignoring much heavier wounds when the situation called for it.

"You're wondering why he wants you in this fight, aren't you, Ishida-kun?" Kyōraku used one of his thumbs to swipe some blood away from the corner of his mouth, frowning at it.

"Yes." There was no point in acting otherwise.

"What do you have that the rest of us don't, I wonder?"

Now hardly seemed the time for being cryptic, but it occurred to Uryū that maybe the question wasn't cryptic at all. On the one hand, the answer was completely obvious. On the other… it didn't seem to explain anything at all. Perhaps Kyōraku only knew the obvious answer, and wondered about the rest—just like him.

Still, Uryū took the hint for what it was, sliding one of Yorugen's blades into his sash and withdrawing a Seele Schenider with his free right hand.

Aizen had referred to him only as a Quincy, after all. Perhaps it was time to figure out why _that_ was the part that mattered to him.

* * *

 _Term Dictionary:_

 _Nula Espada_ – "Null Espada." Anzparrejar exists outside the usual ranking system for the Espada, effectively taking the "zero" spot from relased Yammy for reasons I explained earlier. But because a _cero_ is already an attack, I disambiguated by using "null" instead of "zero." Plus, I like the flavor of the word more. It has a sense of negation or cancellation to it, whereas zero has connotations more like either a prototype/not-quite Espada, or a worthless one. I'm picking nits, but that's a hobby of mine, so please pardon me.

 _Kurohitsugi_ – 黒棺 – "Black Coffin." Hadō #90. Seals the target in an enclosure of black energy, which is then stabbed from all sides with weapons made from the same reiatsu. Basically like that stage magic trick where the assistant goes into the box, the magician stabs the box with a bunch of stuff, and the assistant emerges unharmed. Only without the "emerges unharmed" part.

 _Engetsu_ – 剡月 – "Scathing Moon." Isshin's zanpakutō. The shikai takes the form of a glowing blue-white blade with two long rope or chain-like attachments on the end of the hilt. The signature attack is, of course, _Getsuga Tenshō_ (月牙天衝), "Moon Fang Heaven-Piercer." The release command for Engetsu is _moero_ (燃えろ), the imperative of "to burn." My headcanon is that it's a fire-elemental kidō-type like Karin's, and also that this sort of thing _sometimes_ runs in families.

 _Tsuriboshi_ – 吊星 – "Suspending Star." Bakudō #37. Creates a ball of blue energy which fires out six ropes from its center. As the ropes attach themselves to nearby sturdy objects, the energy in the center solidifies into a flat elastic-like cushion, which catches falling objects.

* * *

Oh man. We're so close to the end now. I'm thinking maybe one more (longish) chapter, or possibly two. Not that the _story_ will end there, of course, but the arc certainly will.


	25. Chapter Twenty-Five: Deicide

_._

* * *

 _Catastrophe Theory_

A Bleach Fanfic

 _Chaos Theory_ AU

Chapter Twenty-Five: Deicide

* * *

Just how many Gillians and Arrancar did Aizen _have_?

Tōshirō couldn't deny that a very large part of him wanted nothing more that to ask him in person while tearing him into very small pieces, but Kurosaki had a point about his mental state right now. Not that he intended to admit that to her, of course.

Still—the horde just kept on coming, pouring out of that garganta like so many drops of rain from a cloud. They were just as hard to avoid as raindrops, too. Getting away from any single one was easy, but not getting hit at all was practically impossible. Gritting his teeth, Tōshirō swung Hyōrinmaru, casting half a dozen blades of sharpened ice off the edge of his sword. They flew true, burying themselves in the oblong mask of the nearest giant Hollow, cracking it in enough places and with enough force that it broke apart entirely, killing the creature it protected.

But turning aside one drop was almost laughable in a storm like this. They needed another method, and quickly.

Beside him, Kuchiki dropped his zanpakutō, summoning his bankai. Hundreds of glowing swords condensed from thousands of tiny blades; they melded into fewer weapons almost immediately after. The problem was that not only were these foes so numerous, but also strong. Five years ago, Tōshirō would have had trouble with more than two or three Gillians, and he was a captain.

Now, they had to be good enough to cope with scores of them.

"We should attempt to cut our way to the others," Kuchiki said, almost tonelessly. One of the swords hovering in the air in front him shot forward almost like an arrow, embedding itself in the forehead of another Gillian. The mask cracked, but did not break until a second sword joined the first.

Tōshirō flashed away from a massive red _cero_ blast. At least these things were slow.

"Fine," he said. "I sense a few to the west." It was hard to get a read any further out, though—they'd just have to sweep the fake town the old-fashioned way if they didn't move within range of anyone else after that.

Kuchiki nodded; together, they set about the grim work of carving themselves a path to the west. Tōshirō was alarmed that he could no longer sense Momo; he hoped that was because she was using a concealing kidō, and not because the worst had happened. She'd been somewhere nearby when he first entered through the garganta, but…

 _They will do as scavengers always do—eat the weak and the dying first._

Momo wasn't weak.

But she might be dying.

Impatient, Tōshirō called up his bankai, moving higher into the air and throwing ice down onto the Gillians from above. With Kuchiki coming in from the front, it was about as close to a pincer maneuver as they were going to get with two people. Aizen's reiatsu flared some distance back; he felt a shift in at least a few others in response. Kurosaki-taichō was slowly building his up as well; his bankai required a lot of that before it could be released.

He wasn't actually too worried, though—he'd seen that release before. Whatever that Arrancar thought he had wasn't going to stand up to it. The issue was in how much would be left by the time those three would be able to add their support to this.

"Hitsugaya!"

The shout came from the same direction they were headed; a moment later, Suì-Fēng appeared. She was wearing some kind of gauntlet that he presumed was her zanpakutō; her other arm was missing almost entirely. The man who showed up a few seconds after had the same problem, but his was capped with a kidō that was apparently stopping him from bleeding. Tōshirō had no idea who he was or what he was doing there, but if Suì-Fēng wasn't concerned, then for now he wasn't, either.

"Is that Kuchiki down there?"

He nodded sharply. "We're trying to gather everyone to fight the Gillians and these extra Arrancar."

She pulled in a breath. Her face was wan, almost waxy—but she was still moving around pretty effectively. "Good. We'll help. Let's go, Hachi."

The man with her nodded; both of them flashed ninety degrees away and started hewing down Hollows from the side.

With the four of them working more or less in tandem, it didn't take too long to reach the first of the others—Ukitake and Kotetsu. There was blood flecked around Ukitake's chin and neck, and more smeared at the collar of his haori, but he didn't outwardly seem to be injured. Kotetsu looked like death slightly warmed over; her hands were shaking visibly. But she stood as soon as they got there.

"Hinamori and the others were south of here when I left them," she said. "They might be cornered—we should try that direction first."

"I may be of assistance with the healing," Ukitake put in mildly, "but I'm afraid I won't do too much good otherwise, at the moment."

Upon promotion to his captaincy, Tōshirō had been made aware of a few little-known pieces of information. Outside of the captains, a few of the fukutaichō, and the officers of the Fourth and Thirteenth, it wasn't commonly-known that Ukitake was ill. Even the captains probably only knew because of the possibility of situations like this one.

Despite his warning, though, Ukitake did pick up his zanpakutō, releasing it into shikai form.

Tōshirō was inclined to get going; he paused for a couple more seconds to make sure no one else had anything urgent to say, and then they were off again.

Wading through the Gillians was enough of a task on its own—mostly he and Kuchiki handled that, with Suì-Fēng and her friend keeping the smaller Arrancar away, flashing around the edges of the zone of immediate battle. Ukitake guarded the rear, and Kotetsu, apparently able to sense more than he could through all of this reiatsu, occasionally called out directions to reorient them.

It was ten straight minutes of constant slashing and _shunpō_ later that they encountered the next group of survivors. Though Tōshirō supposed he was using that term lightly.

None of them were people he recognized, but the only conscious one was wielding a zanpakutō, hurling blasts of fire from the end of it at the Gillians that surrounded himself and two unconscious men. One of them had short silver hair and a build not unlike Kurosaki-taichō's. Oriented towards power and close-quarters fighting. The other was leaner, with what looked like a lot of blonde hair. He also had the third missing arm Tōshirō had encountered in the last half-hour, though it looked to be barely still attached, so technically it wasn't _missing_ , as such.

None of them were the person he was looking for, but he knew what strategy demanded here.

Kotetsu and Ukitake set to work immediately; the rest of them formed a rough circle around the two of them and their patients, fending off Gillians on all sides. It was a massive press of Hollows, and each of them was large enough that it felt like buildings closing in on them—skyscrapers that got even bigger in his vision until basically all he could see was the black fabric of their cloaks. The jagged circle of sky above provided enough light to navigate, still, but it was disorienting nevertheless.

They were too exposed out here in the middle of a flat part of town. Taking the Gillians out one by one just wasn't feasible anymore.

Shifting back to shikai, he fell back on the most primitive and fundamental of Hyōrinmaru's abilities— _Tensō Jūrin._ Raising the zanpakutō, he pushed reiatsu up through the blade and out beyond it. Nearly immediately, the sky overhead began to darken, plunging their hemmed-in area into deep shadow, though not complete darkness. A harsh breeze stirred even the massive, heavy cloaks of the Gillians; thunder rumbled ominously in the distance.

The clouds broke open on command—drops of icy water fell thickly from the sky, slowly dampening the Gillians. Tōshirō ground his teeth—it wasn't happening fast enough. At this rate, they'd simply be overwhelmed by numbers until—

A massive bolt of lightning punched into the mask of the nearest Gillian, shattering it instantaneously. Five more followed, replacing the huge Hollows with electric bars, as though closing them in a cage. Tōshirō tightened his grip on Hyōrinmaru; if this was some new Arrancar…

"Glad you could make it," Ukitake said, apparently speaking to the newcomer. His tone imitated the usual lightness with which he spoke, but poorly. It sounded like he was… _commiserating._

Tōshirō cast his eyes around; but who the hell was he commiserating _with_? And why was he unconcerned with the fact that they were trapped?

A Gillian reached forward towards them. Its hand struck one of the bolts of lightning, and it disintegrated on the spot.

Not trapped. _Protected_.

"Ukitake-san." The new voice was one Tōshirō recognized, an instant before the speaker appeared in front of them. Sasakibe.

"I can't keep this up for too long, with the state I'm in," he warned.

Much of him was covered in heavy burns; whatever had hit him had singed the entire left half of his shihakushō off and blistered and blackened the skin underneath, from around his waist to his jaw or so.

Kotetsu's eyes went wide; she was still working on the unconscious men, but looked unsure for a moment of what she should do. Tōshirō honestly didn't know any more than she did about that—not right now. Not when all he could think about was the people they still hadn't found. And the fact that Momo was one of them.

He turned back to the battle, only half paying attention as Ukitake issued orders. Sasakibe's bankai was strengthening the thunderstorm Hyōrinmaru had summoned; Tōshirō took advantage of it, flash-freezing several more Gillians. Pinkish blades slid easily in and out of the electric bars of the cage, methodically slicing down even more. The man with the club aimed his fire more carefully, and managed to do the same.

They were safe until Sasakibe ran out of reiatsu, and they had no ay of knowing when that would be. Hopefully enough time for Kotetsu and Ukitake to do what they needed to, and hopefully not so much that the shinigami still out there were overwhelmed.

Pulling in a deep breath, Tōshirō closed off the train of thought as well as he could. The more Gillians and Arrancar he could freeze, the better chance they had.

All of them.

* * *

"Bankai: Keizen Hisaku!"

Karin released her zanpakutō, backing away from the old man in the process. Her fire couldn't burn her, but she wasn't great about making its damage selective yet, either; if someone else got in the way, she could hurt them.

But there was no way they were taking this creepy guy down at anything less than full juice, and that was pretty obvious. She was shaking, even; she remembered the way he'd nearly gutted her the first time they'd done this. She wasn't scared all that often—it was actually kind of weird to deal with. The cold sweat starting to slick her arms and her back, the way her shihakushō stuck to her so she could feel every little irritating rub of the fabric on her damp skin.

The way her heartbeat was loud in her ears like a drum.

"Karin." The old man glanced at her from the corner of an eye.

She shook her head slightly, tightening her grip on the tessen and katana in her hands.

"Yeah. I'm here."

Here. Now.

The rest could come later.

He led the way in, releasing a blast from the end of Engetsu. She'd never actually seen him in a fight before—it was hard to get over how serious he looked. Her dad mostly only made stupid, exaggerated faces: big grins, over-the-top pouts, pretend-frowns. He was usually behind her, nudging her forward in his obnoxious, pushy dad-way. Sometimes she forgot he'd been a captain first, and a dad only after that.

Captains led from the front.

The Espada and fake-Yuzu both got out of the way of the _Getsuga Tenshō_ , splitting up and moving to flank from different directions. Since it looked like the old man was going for the Arrancar, she got in the clone's way, flinging half a dozen spears of reiatsu from the wing-shaped blobs of it behind her.

The clone swept them away with a sweep of her version of Hasuhime; it looked exactly the same as far as Karin could tell, but she hadn't used any kidō with it. If this copy was anything like the real Yuzu, though, pressuring her up close would be the best idea. So Karin flashed forward, throwing her tessen directly for the staff.

It caught with a series of clinks, the chain attached to the end entangling the clone's weapon. Karin took a firmer grip on it and yanked forward. Unexpectedly, the clone abandoned her hold on it and moved in instead.

Karin just barely ducked in time—this fake didn't really fight like Yuzu did at all. Her hakuda strikes were all hard arts, aggressive and powerful, not yielding and clever like the soft arts the real Yuzu preferred.

Shaking Hisaku free of the dropped stave, Karin just barely blocked an incoming punch with the tessen's spine. The hit vibrated through the metal, jarring her arm. The clone recovered just a bit faster, seizing the front of Karin's red haori and pulling her closer.

"I already know _you_ ," she hissed in Yuzu's voice. "I know what you cannot cut."

"What are you _talking_ about?" Karin growled, shoving back against her with both hands. She didn't have enough room to use Hisaku, or she would have. This thing was creeping her out.

"Karin!"

That was Yuzu's voice, too, but it was coming from behind the clone. Karin pushed harder, freeing herself from the clone's grip. She was just in time—the spear-point of the real Hasuhime punched through the clone's chest a second later. It disappeared; Yuzu had withdrawn it to move back for another strike. Karin was about to follow suit when the clone abruptly disappeared.

Both of them whipped their heads around, tracking the reiatsu back to where the Espada and the old man were.

The clone materialized at his side, bloody but apparently entirely unconcerned. Maybe she couldn't be hurt like the real thing could? If she was some kind of release or something, Karin figured she might not play by the same rules as an actual person.

She and Yuzu followed, jumping to flank the old man. He didn't look hurt—not physically anyway. But the look on his face—Karin knew that look. It was from a point in their lives before the buffoon-faces were the norm.

This was the way he looked after mom died.

"Dad… what the fuck is going on here?"

He swallowed so thickly she could hear it.

"This… this is the Hollow that killed your mother and brother, Karin. This is Grand Fisher."

* * *

Aizen caught Kyōraku's blades—both of them—and hurled the captain into the nearest building. Urahara threw several red reiatsu blasts at him from the left. Those, he let hit him, apparently unconcerned that they left marks in… whatever casing was protecting his body. Yoruichi, nearly out of armor to protect her limbs, sacrificed the leg protection she had left to deliver a roundhouse to the side of his head.

Uryū took the opportunity presented by the revolving door of distractions to set himself up _very_ carefully. He fed a steady stream of reishi into the Seele Schneider, until it vibrated at the highest frequency he felt comfortable with. Too much, and the particles would lose their cohesion. Not enough, and they wouldn't be able to cut through reiatsu as dense as Aizen's carapace.

They might not anyway, but he had to try.

There were no second chances—this battle was it.

Either Aizen was leaving it alive, or they were. Not both.

Firing a few normal arrows from his bow, Uryū curved them around to the right, letting them fly in from the side as Kyōraku and Urahara stepped back in to continue the fight at melee range. Aizen didn't have to do much work to avoid them—just lean to the side or put up a shield. But he _was_ avoiding them.

Why do that if they weren't a threat? He took the blows the others delivered without seeming the least bit concerned.

But even if he _didn't_ dodge, he _could._ Making sure the Schneider hit was going to be the key here.

 _And so is doing this while your allies are still alive to distract him_ , Lucia warned him, her mental tone edged with reproach.

Uryū's mouth pulled into a scowl; he narrowed his eyes and picked a spot to aim for. Drawing the reishi string back to his cheek, he assumed the most basic of all archery stances: a stationary one. It was basic for a reason: the less movement he had to account for, the more likely he'd be to hit where he aimed.

Over Aizen's shoulder, Yoruichi spotted him.

" _Bakudō #61: Rikujōkōrō_!"

Uryū released on an exhale, the same moment the first of the bars of light from her spell slammed into Aizen's midsection. It wouldn't hold him for long—but the arrow didn't _need_ long.

The Seele Schneider hit full-force right at the back of Aizen's neck. There was a burst and a flash of light; Uryū was forced to shield his eyes. The cracking sound was unmistakable, but…

Blinking as his vision adjusted, Uryū grit his teeth. This couldn't be good.

Aizen stood where he'd been hit—but the shell that had protected him was gone completely. In its place was—well, he looked vaguely like a moth. The wing-shaped protrusions in his back looked to be made of the same stuff as the shell had been.

Not shell. _Cocoon_.

He turned, a strange silver eye with a purple sclera fixing on Uryū.

"That was quite the arrow. I was hoping you'd be able to muster it. I must thank you—adaptive pressure is important to evolution, after all."

* * *

Grand Fisher.

It had been a while since anyone had called him by _that_ name. It was correct, in a way—he had once been the being with that name. Those intentions.

But he was more now.

Beneath his mask, Anzparrejar felt his facial features shifting slightly, adjusting to the new data he gained from the blood on his claws and the images before his eyes. He did not have the capacity to take on the form of a child, but he could call up that piece of himself—nearly amorphous now, but with its memory vaguely intact—and conform it a little more to the way the man looked.

And why wouldn't he? For so long, he had waited for this.

" _Segunda Etapa: Piraña Voraz._ "

The horns growing from the mask fragment atop his head thickened, extending further forward; his _estigma_ drew red lines over the left half of his forehead and the cheekbone beneath it. Anzparrejar felt his vision sharpen and his claws extend into hooks; the sword in his hand compressed and darkened. A soft clink sounded as a thin chain extended from the end of it. At the other end of the chain was a barbed hook, dense enough to be heavy even to him.

Piraña shifted forms, too, losing the appearance of the girl… but only to an extent. She grew several inches taller, her hair lengthening and curling, the color dimming by several shades. Her shape changed, the leanness of active youth replaced with something fuller; her features lost the vestigial traces of childhood. It was too bad, really—they tasted best when they were still just a little bit innocent. A little bit juvenile.

But he would dine on two who stood right on the knife-edge soon; that was enough.

The man looked as though he'd physically been struck, harder than Anzparrejar had yet managed to do. Everyone was weak to something. He had often found that those who stood most easily under the pressure of his reiatsu, weathered his heavy blows with least breakage—those were the ones who buckled at the knees to see someone they loved standing before them, pointing an arrow directly for their heart.

Isshin Kurosaki was no exception.

Anzparrejar dropped his mask.

The dark-haired twin—Karin, his fragmented memories supplied for him—stared with wide eyes.

"I-Ichigo? Is that… you?"

So the contortion was plausible, then. She could believe that she was looking at her dead brother, long years after she'd seen him.

Good.

Heartbreak had the richest taste of all.

* * *

Yuzu felt horror rising within her like a tide; the battlefield alone had thrown her waist-deep, but this… this was…

She didn't think there were words for what this was.

Somehow, though, it all fit together. The unease she'd felt around Anzparrejar; the fact that he always seemed to lurk nearby. Every shinigami knew Hollows tended to go for loved ones. Just like everyone knew that Hollows gained power by consuming souls—souls that sometimes retained their unique identities even after consumption. Speaking with Grimmjow had made it clear that occasionally even Arrancar could still be aware of the other former souls within themselves, even if they degenerated until they were largely without individual personalities.

Was it really a great leap to believe that Ichigo—that their mother—was still recognizably in there somewhere? What if… what if he'd somehow become the dominant persona?

Fighting a false replica of someone you loved was one thing. It would be difficult. But… fighting what might _actually_ be all that was left of them in the world…

Could she do that? Could _they_?

Because that was surely what they faced down now. Their mother—or the image of her—wielded what looked for all intents and purposes like a Quincy bow. Not that different from Uryū's. The glowing arrow fitted to the string was aimed right for Dad's heart. Ichigo—or not-Ichigo, she couldn't say—still wielded a sword. This one was thinner, more like a traditional katana. But the blade was entirely black, and near the front of it, serrated. Tiny gaps in it promised a vicious cut. The hook on the end was a cruel device; she only had to look at it to know that. His eyes had turned yellow, with black sclera.

It was so strange. He looked right and wrong at the same time. She recognized him on a fundamental level… but he was also utterly alien to her.

And her mother…

A zanpakutō spirit was a living thing. Starrk had taught her that in this, a resurrección release was no different. Could it really be that the spirit in this one was some piece of mom?

"Karin. Yuzu." Her father's voice was hard, steady.

She wasn't sure she'd ever heard that tone from him.

"This isn't your mother. It isn't Ichigo. Whatever parts of them are still in there… aren't the family you knew." He pulled in a breath big enough to visibly expand his chest. "You're shinigami. You know what has to be done here."

Yuzu swallowed. There were so many facets of this she hadn't considered. So many implications she knew she needed to look at more carefully, understand more thoroughly. But there wasn't time.

Her allies were in danger. Some of them were probably dying. And whoever this was, whoever he had been, Anzperrejar was threatening the friends and family she had left. No one she would recognize as her mother, no one she would recognize as her nii-chan, would ever do that. Her hands tightened; Hasuhime was cool and firm under her grip. Just like she needed to be right now.

" _Bakudō #42: Midoriami_!"

The net shot towards Ichi— _Anzparrejar_. It stretched wide, and then—

An arrow shot it out of the sky, dissolving both in a burst of reiatsu. It didn't feel anything like Uryū's arrows did, but… it looked exactly the same. It was the same kind of wrong and right at the same time as everything else about this.

Yuzu wished this was a nightmare.

She wished she could wake up.

But it wasn't—none of this was. This was all the real, ugly, messy reality of the situation, and she had to face that. Small and weak as she felt against it. Fragile as her resolve felt when the faces she looked into were those of people she loved.

She'd already looked into the faces of her enemies and seen the allies they could be. Now she had to do the opposite.

It was much, much harder.

* * *

Yuzu threw another kidō at the creature that wore the face of his first child. This time, the arrow Masaki's doppelganger fired only managed to put out part of it; the rest of the _shakkahō_ made it to the Espada, though he turned it aside with his own zanpakutō.

She shouldn't have to fight alone. He believed everything he said—these people were _not_ Masaki and Ichigo grown. For the sake of his wife and son, he had to kill this Arrancar, so that their souls could find their way to Soul Society to be reborn. That was the bottom line here.

And he wasn't going to be able to do that if he kept fighting at half-steam. Their opponent had some formidable reiatsu. Isshin had to bring his to bear again, too.

 _Ready?_

 _I am always ready. You're the one that hesitates._

"Ain't that the truth?" he muttered.

He couldn't hesitate now, though: Isshin knew he'd lose his resolve if he did. So, like flipping a switch, he made the decision, and allowed no pause before he went through with it.

" _Bankai: Engetsu Naien_!"

Isshin's reiatsu reversed direction; what he'd been exuding returned towards his body, sinking into his muscle fibers, nerve endings, and bones. It had never been a painless process, but considering how long it had been since he'd used the release… It didn't surprise him that his vision nearly whited out. It felt like all his parts were being broken down, then sewn back together, though nothing outward changed.

Still, the _feeling_ of being in his own body was different. Thoughts became actions almost faster than he could keep up with; what before would have been a simple tap now had enough force to throw someone three times his size half a block. Fortunately, the Engetsu still in his grip was stronger, too—enough to withstand the force with which he could swing him, anyway.

Isshin surged forwards, avoiding the construct that looked like Masaki. The other was stronger—and he needed to keep him away from his daughters. He swung Engetsu in a controlled arc; it clanged off the Espada's blade with a screeching bang. The sound set his teeth on edge, but Isshin bore downward all the same, testing his strength against the Arrancar's.

It was his foe that had to break the lock; he jumped away and threw a blast of reiatsu from the end of his sword. It was similar to _Getsuga Tenshō_ ; that more than anything confirmed to him that Ichigo must be in there, somewhere, in some form. He'd recognize the technique's feel anywhere.

It should have been the birthright of his son.

Should have been something Isshin taught him.

But it wasn't.

He braced to meet the attack with one of his own, but before he could, red closed in all around him, a curtain of reiatsu that blotted his view of the rest of the town. He turned, glancing over his shoulder and down. Karin stood in the sphere with him, Yuzu at her side.

" _Bakudō #81: Dankū._ "

The kidō shield reinforced Karin's wing-sphere just in time: they all felt the impact as the black _Getsuga Tenshō_ collided with their outer layer.

"Drop the shield as soon as it's over," he said. His eyes flickered between them.

Karin still looked uneasy; her expression wavered. Yuzu, on the other hand, seemed more resolute, and nodded firmly.

"Remember what you're fighting for, girls," Isshin continued quietly. "This is the only way to free them."

The red sphere finally broke under the pressure; the attack slammed into the _dankū_ as well. But it had lost enough power that though the second barrier cracked, it did not break. The moment the way cleared in front of them, Yuzu dropped the kidō. Isshin lunged.

* * *

"Shit."

Karin dove to the side, narrowly avoiding the arrow her mother fired.

No. Not mom. She had to remember that.

But it was really hard—this… resurrección or whatever it was looked _exactly_ like the memories she had left of her mother's face. She'd only been eight years old when she lost her, but… even after all her other memories from the living world had faded or disappeared, those ones were still pretty clear.

And they looked like this.

"Karin!" Yuzu flinched, taking several steps to the side.

Dammit. The longer she stayed in bankai like this, the harder the fire got to keep hold of. It was like… well… _trying to keep hold of fire_.

"Sorry, Yuzu. Just… try and stay clear. I dunno how much longer I can—"

Two more arrows incoming. Karin swung Hisaku's fan, throwing an arc of flames out to meet them. Though they should have incinerated in the air, it seemed she didn't apply enough power, because they were still heading towards her.

Yuzu intervened, striking them directly out of the air with a swing of Hasuhime. The staff's rings jingled with the force of the hit; the sound was way too… pleasant, for a battle. Not like that racket dad was making.

"Karin, Yuzu…"

Karin's eyes went wide. It was the first time she'd heard Mo—the _illusion_ speak.

She sounded just like her, too. That same patient gentleness.

She lowered her bow, relaxing the draw partway and regarding them with soft, dark eyes. "Please… don't do this. My girls—I don't want to hurt you."

Karin heard the strangled choking sound that came after the words—but it took her several seconds to realize that _she_ was the one who'd made it.

No.

No, this wasn't _fair._

Hadn't they suffered enough? Hadn't _she_ suffered enough? This was something she'd _dealt_ with. Badly, and then better when Hisaku forced her to at the academy. It still hurt, sure, but it was old pain. It wasn't supposed to ever be a fresh wound again. It _wasn't supposed to be like this._

"Shut _up_! You're _not_ my mom!" Karin felt the fire slipping away from her, passing through her control like it would burn through dry underbrush. Reiatsu poured outwards, from the vents in her wrists, from the damn pores in her skin. Too much of it, feeding the fire that surged around her, leaping up towards the sky.

"Karin, no!"

She thought she heard a distant voice, but it was too soft over the roaring of the fire. It fed on her pain, spread outwards from the center point of her body and _ate_ and _burned_ and it _hurt_.

But Karin didn't care. She howled her fury and jumped forward, dead-set on destroying this _thing_ that was wearing her mom's face.

* * *

Yuzu watched her go with a mixture of trepidation and outright fear. Karin's fire was only spreading—that was a potential danger to other people in the area. But just as much of a problem was that it wasn't as focused as it needed to be. The chance of it doing more good than bad was slim.

And Karin didn't quite seem to be able to see that.

She glanced left—Dad was still locked in combat with Anzparrejar himself. They looked to be really evenly-matched; she couldn't risk distracting him or it could all be over. That meant if anyone was going to be able to contain this fire, it had to be her.

But how?

Karin's fire was kidō-like; Yuzu knew that. That meant it should interact with other kidō in the ways she'd learned about already. She had that going for her, anyway. The flames were wild and poorly-controlled, and Karin just seemed to be letting her reiatsu pour into them without much caution. It was something Yuzu could _understand_ , but not exactly what they needed right now.

So it came down to finding a way to make the bad situation into a better one. To contain and concentrate the fire, and direct it where they needed it to go.

She didn't think too much about where that was, exactly; having the puzzle to solve was doing wonders for her own clarity. She couldn't afford to lose that.

Containment. Control.

" _Bakudō_ _#81: Dankū_." A translucent, pink-tinged barrier spread outwards from Yuzu's fingertips, extending towards Karin and Piraña, or the reiatsu construct that Piraña's release had made. It was hard to differentiate, and not important right now.

Normally, _dankū_ were used as barriers, walls between oneself and hostile kidō. Yuzu bent hers so that it started to dome over Karin's fire, cutting off its ascent. Her sister had said Hisaku never burned her. Yuzu had no choice but to believe it was so.

Containing the fire proved difficult; Karin was putting a _lot_ of reiatsu into it. Yuzu was forced to use more than she was comfortable with reinforcing the kidō, but she managed. Shaping it outwards, she brought the ceiling of it down, then formed funnels with it as well, keeping the spell moving with Karin. It wasn't much danger to anyone else now, but trying to direct it specifically with tubes made of kidō was a struggle. Both Karin and the being who looked like their mother were fast, and moving around a lot.

But she did have some success.

A surge of fire from Karin fed smoothly into one of Yuzu's kidō funnels, and she aimed it just in time to blast an incoming Piraña as she tried to flank. She probably would have just hit the _dankū_ at that angle, but Yuzu didn't want to risk it breaking. Piraña's clothing caught fire; she shrieked and fired several more arrows at Karin.

Karin knocked two out of the sky with her zanpakutō, but the third one had curved. It was coming in from below—and Yuzu wasn't shielding that angle. Expanding the kidō would take too long, and she was running out of reiatsu. Karin wasn't in any shape to take heed of a warning.

Yuzu acted.

"Karin, move!"

She wasn't sure she'd ever flash-stepped as fast as she did right then. She still almost didn't make it—she had to bend at the waist to reach Karin, shoving her sister out of the way as hard as she could. It occurred to her that the burning she smelled was due to her own skin and clothes—that was the last thought she had before the arrow slammed into her gut.

She fell.

* * *

" _Yuzu_!"

But Yuzu was falling.

She tensed her muscles to follow, but _she_ got in the way, firing another volley of arrows all at once.

Karin lost whatever hold she had left on the fire; it climbed into the sky and fizzled out. The loss left her only with her sword and her tessen, and whatever fight she had left in her.

She knocked half the dozen away with Hisaku's blade, flashing out of the way of the others. This had to end— _now._ Not eventually, not soon. Not whenever she could muster the power, or a strategy. Just. _Now._

She flew forward as fast as she could push herself. Her muscles strained under the force of the _shunpō_ steps; her knees clicked hard as she landed out of the jump, swinging her katana. The fake version of her mom blocked with the bow she carried; Karin threw the tessen, trying to get it around her neck. She caught the chain midway with a hand; it wrapped around her arm instead. Karin yanked, pulling her forward and down and driving her knee upwards at the same time.

There was no mistaking the wet crunch of a nose breaking, nor the warm blood seeping into her hakama. With her other hand, she brought the tsuka of her sword down on the back of the woman's head. She was past seeing her mother in this thing now. All she could see was someone who'd tried to kill her sister.

And Karin couldn't forgive that.

She didn't escape unscathed—a heavy blast of reiatsu caught her in the abdomen. A kidō? One more thing her real mom wouldn't have been able to do, then. And the Quincy bow wasn't right either. And how had she even for a moment been fooled by this?

Backing off, Karin put a hand to the burn wound on her side and hissed at the pain it caused. Her vision was a little fuzzy. Either the pain or her drained reiatsu was doing that—maybe both. She'd wasted too much of it feeding her fire—she saw that now.

But it wasn't too late. Not yet. She could still pull through here.

For Yuzu's sake, she had to.

Dad appeared beside her, bleeding from a cut in his eyebrow and a deeper slash wound across his chest. He was sucking air in like a bellows, but he was still using bankai, too, apparently.

"What happened to Yuzu?" he asked, tone urgent.

Karin shook her head. It was her fault—but if she was going to have a chance at fixing it, she had to swallow the guilt for now. It'd come back up later like something rotten she'd eaten, but that was fine. As long as it stayed down for now.

"She's alive, but…" She was probably unconscious. Karin hoped it wouldn't get any worse than that.

From the corner of an eye, she saw his expression shift for a second; he let out something that sounded like a relieved sigh.

"He's got her."

Karin wasn't sure which he—she couldn't sense it—but she figured dad's relief was good enough.

Yuzu was going to be okay. She had to be.

"I'm ready, Dad," Karin said, tightening her grip on Hisaku.

"Good," he replied. "With me."

As one, they surged forward, swapping targets at the last second. Grand Fisher or whatever, the Espada, had been expecting a heavy, hard blow from Engetsu, not a swift, low stroke from Hisaku. It landed; Karin felt her mouth curl when his hamstring snapped audibly. There was no time to be satisfied, though: high-speed regeneration was a bitch to deal with, and she was willing to bet his was impressive.

She felt her dad coming in behind her; Karin delayed her flash step until the last moment to disguise his approach, then dove away, bringing her blade up to cut down two arrows flying for his back. They disintegrated in a cloud of smoke.

All the reiatsu Karin had left went into Hisaku's blade itself, until the air around it started to shimmer from the heat. She remembered her fight with the spirit for bankai. Remembered what it had taken to get in close enough to an opponent who was nearly untouchable. And she found that thing again, opening her guard just enough to be noticed.

The puppet with Mom's face saw it and went for it, stepping in closer to fire point-blank. That close, there was no way Karin could close the gap in her defense fast enough—but she didn't even try, lunging forward instead.

The arrow thudded into her shoulder; she'd already switched hands with Hisaku, dropping the tessen and thrusting forwards with the blade.

It pierced the puppet's chest, meeting resistance when it scraped one of her ribs before bursting out the other side. The hissing sound could only be the blade boiling the blood and offal on itself. Karin turned up the heat.

The puppet shrieked as she was incinerated from the inside. It cut off abruptly as she burst apart. The sudden loss of support threw Karin forward a bit.

And suddenly, the Espada was there.

A clawed hand closed over her shoulder, stabbing her with what felt like steel needles and yanking her forward. His teeth closed over the spot her neck met her shoulder, and it was Karin's turn to scream.

As quickly as he'd appeared, he was torn away; his claws left bloody furrows in her shoulder, but that was nothing compared to the pain of the bite. Karin's vision whited out.

The last thing she saw before she lost consciousness was her dad running the Espada through.

The expression on his face was murderous.

* * *

"Yoruichi."

Kisuke reached inside his loose shirt, producing a capped needle and syringe from an inside pocket. He tossed it to her with a flick of his wrist.

She grimaced—clearly, she didn't want to leave the fight, dangerous as it was. But Kisuke was thinking beyond the fight, and there was a chance that Karin Kurosaki needed what was inside that syringe. Very much.

"You sure it should be me?" Her glance slid to Uryū for half a second, attacking Aizen in tandem with Kyōraku.

She wanted to spare him the danger. Kisuke could understand that. Better than he thought he'd be able to, actually. He felt the same.

But right now, it was what he _knew_ that mattered. Not what he felt.

"Yes."

She required no further confirmation. Trust filled in the gaps in his words, the way it had for a very long time now. She flashed away to where the second Kurosaki had fallen.

Kisuke returned his attention to Aizen. Leaving aside the fact that _evolution_ wasn't exactly the right word for this—evolving was something a species did, not an individual—the change in his constitution, the makeup of his spirit-body, was formidable. Kisuke thought it fitting to describe it as a mutation—the slight pejorative flavor to that word sat nicely with him.

Less nice was the corner he'd effectively backed them all into. Kisuke could tell that anxiety and even fear weighed heavily on the other two—perhaps on everyone else on the field, if they had the time to spare for it. He was less concerned, but it was also vital that he did not tip his hand now. There were still ways this could go wrong. The crucial thing to do was to push Aizen to dig even deeper, to tap further and further into the energy he was trying to integrate with his body.

Any organism could only grow so fast. Any rubber band could only stretch so far.

It was their job to make sure that Aizen in his arrogance pushed too far, pulled too tight, grew too fast—

And snapped.

Now seemed like a good time to call in a favor, then.

" _Jigoku no Ken_." Kisuke shifted his reiatsu, drawing it back over himself like a cloak. The familiar feeling of it was interrupted somewhat when it took on a faint tinge of what he'd picked up in Hell—but that was the very point of the technique.

Benihime's revulsion was obvious; he could feel it rebounding through his inner world as the sky over her castle grew dark and her air gained the distinct scent of sulfur.

But Kisuke chose to ignore that, solidifying the mixed energy and feeling it settle around him as a spiritual object. The coat was, if anything, a jinbaori. But of course he had no great lineage, to have come by such a thing in the usual way. Instead, it was emblazoned with the heraldry of hell itself—a solitary, withered tree enclosed in a white circle made up the mon. The rest of it was ordinary enough in appearance. Red, gold, and black silk, mostly. It sat like any haori did, though the weight was much heavier. Unsurprising, given the density of the reiatsu involved.

The abrupt change caught Aizen's attention, naturally, and he appeared in front of Kisuke, firing a blast of raw energy point-blank.

Kisuke brought up Benihime to form a shield. As expected, it didn't hold up under the pressure, and most of the blast hit him head-on. He shifted upwards on his geta, his feet dragging along the air-surface he'd made for himself. But it only pushed him back several meters instead of several hundred, and the impact itself dispersed over the armor.

"What's this?" Aizen tilted his head, regarding Kisuke with a curled upper lip.

He considered that fortunate—Aizen's first response had been to strike with power and no finesse, and already he was looking for a way to underestimate the development. Kisuke could only suppose the Hogyōku itself was influencing his strategy. The Aizen he'd once known prided himself on knowing before acting, and most often knowing more than anyone else.

It was why he, and not someone like Yamamoto, had fallen into the role of opponent. Aizen, not Kisuke, had chosen how this war was framed. Kisuke had only decided to play the role he was assigned.

"I see your time in Hell was well-spent."

"Do you?" Kisuke drawled. "I'm not sure you see anything anymore. It's almost disappointing."

Aizen's brows descended over his eyes. "On the contrary, I am the one who is disappointed. Five years to prepare, and your strategy comes down to this? This is your final maneuver—the last obstacle to stand before me?" He shook his head faintly.

They were interrupted by the heavy whistle of a _Heilig Pfiel_.

"I wonder," Kisuke replied, intentionally coy.

Aizen dodged the arrow; it skimmed his sleeve and left a ragged tear, but did not draw blood. Kisuke lunged while he was still off-balance, feinting with Benihime. When Aizen moved to block, he twisted away, thrusting out with a hand.

" _Hadō #73: Sōren Sōkatsui_." The twin flame ropes snapped outwards; one of them wrapped around Aizen's left forearm.

He looked down at it dismissively, blasting the spell apart by exerting his reiatsu.

" _Hadō #78: Zangerin._ " Kyōraku's attack was next; he aimed the blast low.

Rather than move high, Aizen blocked it with more reiatsu, forcing the spell to disperse. Kyōraku was breathing heavily—Kisuke was honestly surprised he was still able to use a kidō that high in the ordering. Then again, that generation did have some pretty scary reiatsu themselves, didn't they?

That was good. The more they had to throw at him, the more Aizen would use to thwart them.

And if they could last long enough… that would be his undoing.

* * *

When Yuzu fell, Coyote caught her.

It only seemed fair, considering everything that had happened.

The bolt of reiatsu was still embedded in her belly; he left that alone for now. It was probably preventing her from bleeding out, and he was no healer. Hooking one of his arms under her knees and the other around her back, he tried to avoid jostling the injury too much, though that was not a nonissue, considering the surroundings.

He could sense the Gillians looming over him without seeing them or even their long shadows. Whatever natural instinct they had to avoid his power wasn't working at the moment. Perhaps they couldn't even properly sense him. He'd have preferred that they stay away, but since they were intent on eating him—or more likely, Yuzu—he fired several _ceros_ from a standstill, blasting each one in the mask.

He thought he could detect a reiatsu he'd sensed once before, just now entering the area. The woman—the one who'd been there when he retrieved Yuzu on Aizen's orders. If he recalled correctly, Yuzu's division comprised healers, and that woman was the captain. If so, it was obvious what he had to do.

Getting there, however, would be a chore. While Coyote supposed he might repel at least some of the Gillians simply in virtue of being what he was, the opposite was true of the Arrancar. Perhaps they supposed that killing the Primera would earn them the spot, should Aizen emerge victorious.

They could have it.

But of course, there was no reasoning through things—not now. They didn't have the inclination, and he didn't have the time.

So Coyote turned his power upon those who had once been his allies. Again.

He passed by a cluster of fallen and fighting shinigami. Several wore badges on their arms, like a few of the intruders. He assumed they were officers of some kind. A small girl with short, dark hair hurled a ball of fire at a Gillian; beside her, a man with a tattooed face threw a peculiar blade on the end of a chain. Coyote could sense more shinigami approaching. They would be fine. Yuzu might not.

He stepped into _sonído_ , letting it carry him further towards Yuzu's captain.

* * *

Uryū wasn't sure how much further he could push his body before it gave out.

Mentally, he was still fully in the fight. It was discouraging how little anything seemed to harm Aizen, but he, Urahara, and Kyōraku were holding their own well enough for now. If he was reading Urahara right, they were waiting for something to happen. What that something was, he had no idea—but he hoped it happened before he passed out from sheer exhaustion.

His reiatsu had been restored and his injuries healed from his fight with Ulquiorra, but it wasn't the same thing as a good night's sleep, something to eat, and a week off from work. That was certain.

He jerked backwards just in time to avoid a full-force kidō blast from Aizen. His tactics had shifted; whatever armor Urahara was wearing prevented him from taking too much damage at the moment, and so Uryū and Kyōraku were taking the majority of the hits.

In the smoky wake of the _raikōhō_ , Aizen appeared directly in front of him. Uryū shortened his step, taking a hard half-stride back onto his left leg to try and use _hirenkyaku_ faster and get out of range—but it wasn't quick enough. Not quite.

Aizen's hand closed over his _zeichen_ , ripping the chain free of his wrist and crushing it.

 _Damn._

The reishi Uryū had already collected in the object had nowhere to go; without anyone controlling its flow, it backed up and burst apart, throwing Aizen several feet away and enabling Uryū to scramble elsewhere.

This wasn't good. Without his _zeichen_ , he couldn't summon his bow. Couldn't properly direct reishi. His Quincy powers were as good as done for, at least for the duration of this battle.

 _You're being dramatic._

Lucia didn't seem impressed by his logic. Any answer he could have given was delayed by the need to get out of Aizen's range, though. Uryū unhooked Yorugen from his belt, readjusting his grip on both blades.

 _I'm being realistic, unless you know of some other zeichen just laying around somewhere._

She sniffed at him. It was still occasionally bizarre, being able to know that sort of thing without actually entering the Inner World. More difficult, quite distracting—but possible.

 _Does not having your zanpakutō make it impossible to use kidō? A zeichen is a focus, but it is only an object. You are a Quincy—no piece of metal makes it so._

A crash sounded across the field; Aizen had apparently moved on to other targets. A plume of light grey smoke billowed from the side of a building; it would appear he'd put either Urahara or the captain through it.

 _He believes you're no longer a threat. But he isn't thinking much anymore, only destroying._

He supposed she might be right about that. Pursing his lips, Uryū attempted to gather reishi from the air surrounding him. If he could re-form his bow without his cross, he may yet be able to help the others resolve this.

It fizzled out, dispersing back into the environment.

 _I need a focus._

 _So use what you have._ That, surprisingly, came from Yorugen.

What he had? But right now, all he had was…

 _Exactly._

Though ordinarily he'd have questioned them both on this until he was satisfied of the soundness of the suggestion, there really wasn't time for that just now. The other two were still up, but Kyōraku had a brand-new massive gash across his chest. It was bleeding at an alarming rate. If they were taken from three to two, there was no telling how the balance of the fight would shift, exactly. He might find himself under too much pressure to try anything.

Recalling something he'd once done in a practice match against Urahara, years ago now, Uryū tried again to gather the energy he wanted. This time, he focused it on Yorugen, swathing the blades in reishi in a similar way to building a Seele Schneider, only over something else. It stuck surprisingly well—it wasn't hard to vibrate the particles in the usual way, sharpening the edges of the zanpakutō.

The downside here was that he no longer had range. If he wanted to do anything useful, he had to get in close.

* * *

When Uryū's reiatsu changed, Kisuke knew it was only a matter of time.

He could sense the instability in the Hōgyoku. Aizen, now nearly fully integrated with it, clearly could not. There was nothing better for breaking apart spiritual energy bonds than a Quincy.

The math was plain as day.

But contact would be required; Uryū's first pass missed. Aizen ducked to the side and blasted him with reiatsu. The air thickened with it, pressing down on all three of them.

"I grow weary of this charade."

The pressure spiked again; he had to be drawing that directly from the orb. Moving became a lot harder; though Kisuke's armor blunted the worst of it, Kyōraku was not so lucky. He lunged for Aizen, only for his shunpō to fall abruptly short of where he'd intended; he crashed facefirst into the ground. Unlike every time before, he did not rise.

Kisuke stepped in, blocking Aizen's attempted deathblow with Benihime. His Hell-tainted reiatsu gave him a little bit of breathing room here; he'd trained under oppressive pressure like this on purpose. But he was still slower than he'd like to be; Aizen's other hand drove for his abdomen in a kidō-infused strike much heavier than anything Yoruichi had ever hit him with.

He dug in, grunting and weathering the blow instead of letting himself be flung away. Uryū needed time. He was almost there—almost where Kisuke believed he could go. If this spiritual pressure didn't push him to it, then he could not be pushed. But Kisuke believed he could.

And he was hanging his plan on that belief.

Knowing that, Kisuke dug into his own reiatsu reserves, launching a barrage of high-level Hadō to keep Aizen occupied and moving. Whether he dodged, blocked, or snuffed them out with more reiatsu really didn't matter. All of them would consume his resources, and that was the only thing that mattered.

On the heels of a _raikōhō_ , Kisuke flashed in; Benihime sliced across Aizen's chest, skittering over the Hōgyoku still embedded there. As if rejecting the contact, the orb itself repelled her, forcing his guard open and leaving him vulnerable to a counterstroke.

Even under the armor, Kisuke felt his ribs snap when it landed. Losing his traction, he stabbed Benihime into the ground to prevent being launched too far. Even maintaining his hold on her sent jarring bolts of pain through his torso. Cold sweat broke out almost spontaneously on his face and neck—but the strain alone did not loosen his grip. His zanpakutō dragged through concrete, but brought him to a stop fifty feet or so from Aizen.

He hardly landed gracefully, but at least he kept his feet. Pulling in as much air as he could, Kisuke lifted her, resetting his feet and preparing another kidō.

Uryū had stepped in; the blades of his zanpakutō were wreathed in a pale blue light—it was one that Kisuke recognized. Slashing low, he grimaced when Aizen twisted away from the blow. The hand that grabbed for his neck passed through him as though he were air.

Like a volcano, the force of Aizen's reiatsu continued to build.

But Uryū's power was building, too. The more difficult it became to stand beneath the force of Aizen's spiritual pressure, the more his Quincy abilities fed on that same energy, breaking it down and converting it into pure reishi. It gathered, silver-white, near of all places the crown of his head. Kisuke could sense its instability even now—the light wavered at the edges, as though it desired solidity but could not achieve it.

Both of them threatened to erupt, to burst apart and lose their vital coherence. The balance was delicate.

What tipped the scales was not something either of them did.

It was not something Kisuke had done—not directly.

It was something that must have occurred before the battle had even begun.

Aizen's eyes went wide. In his chest, the Hōgyoku ruptured, then burst apart, separating into tiny purple and blue pieces that faded into nothing.

For a strange moment, everything was still, balanced on a knife-edge of silence.

Kisuke released the last piece of reiatsu he needed to trigger his trap.

" _Bakudō #100: Jigokujō_."

The seal took effect, harnessing the energy of the disruption to reinforce itself. Luminous red chains pinned Aizen in place, staking him to the sigil that appeared on the ground. He struggled against it, but the reiatsu he used to do that simply fed into the chains themselves. A rather insidious little thing—a spell that got stronger the more effort the target used to free themselves.

Aizen's eyes snapped to Kisuke. "This is your doing."

It wasn't a question.

"Yes," Kisuke confirmed. "In part." He glanced beyond Aizen; Uryū's exertions, temporary as they might have been, had drained him; that much was easy to see. He'd collapsed; Kisuke could see the steady rise and fall of his chest, but his eyes were closed.

"Before you achieved complete transfiguration, I fired that kidō into your body on the back of another kidō."

"Then…?"

Kisuke sheathed Benihime at his waist and let the _Jigoku no Ken_ disperse. "I thought that if you managed to fully fuse with the Hōgyoku, you would become all but impossible to kill, so I devised this seal, modified from one I invented in Hell. It relied upon you using too much of the Hōgyoku's power, enough to exhaust you and it."

No power source was limitless. Both of the orbs were made with highly-compressed energy; but the amount in each was still finite, as was the amount that Aizen himself contributed. There was no such thing as power without boundary—his mistake had been assuming that such an amount of it would be close enough to limitless that he didn't need to worry about managing it.

Well… one of his mistakes, anyway.

"I'd intended to destabilize it somehow as well, of course—Uryū was quite helpful in that way. But it looks like someone already did some of my work for me, right?"

It seemed to occur to Aizen only then. Kisuke huffed softly from his nose.

"I guess even you can be fooled by an illusion, if you aren't expecting it. Mice bite, you know."

Aizen's lips pulled back from his teeth in something like a snarl. "I despise you. You possess such a great intellect, and yet you do not act. How are you able to let yourself be ruled by a thing like _that_? Surely you see all the ways in which something else would be better. Surely you see all the flaws in how things are."

Kisuke blinked. "A thing like _that_? You mean the Soul King, right? I guess you've seen him." He sighed, glancing around for a moment at the wreckage the fake town had become. "Without the Soul King's existence, Soul Society would be rent asunder. Things as they are would cease to exist. That's just the way it is."

"Those are the words of the vanquished," Aizen spat, all trace of polite civility gone. Defeat could do that to a person, perhaps. "Victors must always speak of the way the world _should_ be, not how it is!"

Kisuke stared at him for a long moment, then shook his head. "There's no easy path to 'should be,' Sōsuke-san. Take it from someone who's looked."

* * *

Rukia raised a hand to knock on the door in front of her, shifting the bundle under her other arm to rest on her hip. She smiled for a moment when the voice on the other side told her to enter, but smoothed it away from her face before she actually did.

"Hey," she said. "Feeling better?"

Ishida's lips thinned into a line; she felt her smile returning. Someone had finally found him another pair of glasses at least. Maybe Nanao—because it looked like they'd come with a small stack of paperwork.

He caught her looking at the pile and sighed audibly. "Mission reports," he said dully. "I don't think I realized how much we actually just did until I had to write it all down."

She could sympathize. Crossing the room, Rukia set the bundle down in front of him. "Lunch," she declared, taking a seat at one of the chairs near his bed. "I asked Isane; she said it was okay for you to eat this instead of the hospital food."

"Who made it?" he asked, a faint note of suspicion entering his voice.

She resisted the urge to scowl at him. "Not me, okay? It was Yuzu. I tried to help, but she mostly ended up doing everything anyway." She'd tried to make lunch for the both of them once. It hadn't really worked out the way she'd intended.

Ishida untied the knot at the top of the bundle, separating the parts of the bento box out in his usual meticulous fashion. She wished she could say she wasn't accustomed to seeing him in a medical facility, but they _had_ been here before. At least it was less awkward this time.

He proffered one of the box's tiers to her; she recognized a peace offering when she saw it, and accepted. He always gave her the good part of his lunch—or let her take it, whichever. She didn't decline; it was a kindness that neither of them acknowledged as such, which was why it continued.

"How…" he seemed unsure how to finish the question, picking up his utensils with his left hand and furrowing his brow. "Is there a polite way to ask who made it?"

It had been three days, but for some the recovery was only beginning. Others still lingered between life and death—it wasn't certain which of them would make it and which would not. She wasn't surprised he hadn't heard yet.

"I asked nii-sama this morning for an update," she said quietly. "I'm sure they've told you that Karin-chan and Yuzu-chan are stable. They took a lot of damage, but they'll be okay."

He nodded, indicating that he'd heard.

"The rest of the Hueco Mundo group is fine—you already know about Zaraki. Yachiru is… no one seems to be sure where she is, exactly, but she'll probably show up again soon. I think she just needs some time. Kurosaki-san's doing okay—he'll probably be by to visit you in a bit, considering how much time he spends here."

Rukia sighed, beginning to tick names off on her fingers. "Kyōraku-taichō is under the direct care of Unohana-taichō right now, but he'll be all right. He's already awake and talking, so there isn't much more to worry about. Urahara and Yoruichi are already back in the real Karakura Town. We lost Komamura-taichō. Hinamori-san and Hisagi-san are awake; Izuru-san is… they're not sure about him. A couple of those strange fighters with the masks are still critical; Iemura-san is treating them in the living world since they refused to come here."

Apparently, they were still technically fugitives, and until that status was changed, it was probably smart of them not to want to be here. She was sure Urahara and his friends were helping, too, which was probably the next best thing to having Unohana or Isane working on them.

"The Sōtaichō is gone." That more than anything was incredibly difficult for Rukia to believe. And yet… she'd seen it from the command room, with Nanao and Renji and a few of the others. "Sasakibe-san has… his burns are really bad, but they won't kill him. Everyone else is somewhere between okay and dead, I guess."

He frowned at that, but made no attempt to refute it. "And Aizen?" He raised another bite to his mouth; only then did Rukia realize she'd been neglecting to do the same.

"Awaiting trial. The new Central 46 is still being assembled, but as soon as they are, they'll be hearing his case." He could rot in the Mūken for all Rukia cared.

Ishida bobbed his head slowly. "Are you all right?"

She snorted. "You're the one in the hospital bed, Ishida."

"Perhaps, but I only fought my enemies."

Someone must have told him about Aaroniero. Rukia swallowed, but found it surprisingly easy to let the feelings pass. What they left behind was a quiet certainty she'd only rarely felt before.

"And so did I."

The corner of his mouth twitched into an almost-smile. "Fair enough." He paused. "This isn't going to end here. So much has happened… things are going to change."

He wasn't wrong. Power in the Gotei 13 was concentrated into the hands of the captains, especially the Sōtaichō. After everything, six of them, including the Sōtaichō, were dead. Iba was gone, and it was hard to say whether Izuru would survive or not. Any way they looked at it, things had been shaken. How they would even begin to recover wasn't something Rukia was sure she knew. She didn't envy the decisions the next Sōtaichō would have to make.

"Yeah," she said. "They are."

* * *

 _Term Dictionary_ :

 _Tensō Jūrin_ – 天相従臨 – "Subjugation of the Heavens." One of Hyōrinmaru's basic powers, as well as its strongest, it allows Hitsugaya to control the weather in the immediate vicinity, or more specifically, control the water in the surrounding atmosphere. The ability is usable in both shikai and bankai.

 _Anzparrejar_ – From _emparejar_ , which means "to duplicate" or "to twin" and _el anzuelo_ , which is the word for a lure in the sense of fishing lure. Since all the Arrancar have names with a doubled letter, I added the extra r. In case anyone was wondering whether or not I just pulled that name out of the ether at random. The Nula Espada, who was at one time the Hollow known as Grand Fisher. He killed and ate both Masaki and Ichigo Kurosaki, and in doing so, also ate what was left over of the experimental Hollow, White. White and the Grand Fisher were the dominant components of Anzparrejar, who Aizen turned into an Arrancar with the Hōgyoku. It wasn't really Masaki or Ichigo in the important sense, but their spirits were technically in there, as were some of their memories and such, which allowed Anzparrejar to take on their appearances and act somewhat convincingly as them.

 _Piraña Voraz_ –白切歯肉食魚 真捕食 – The kanji are "White-Toothed Carnivorous Fish, True Predation." The Spanish is "Ravenous Piranha." Anzparrejar's Segunda Etapa. It looks a fair bit like Ichigo's bankai, for the obvious reason that Ichigo's reiatsu is a large chunk of Anz's power, but there are influences from the other sources in there too: White and Grand Fisher being the big ones. Masaki, of course, provides the shape of the big ball of reiatsu that was the initial resurrección, which remains active.

 _Engetsu_ _Naien_ –剡月内炎 – "Scathing Moon, Inner Flame." Isshin's bankai. Never shown, but sometimes referred to in canon. It's described as being difficult to use, and to require a "fixing" of reiatsu that isn't possible if Isshin is already heavily-injured. Extrapolating from those qualities, I decided that it likely made some kind of alteration to his body itself. So in headcanon and here, the bankai focuses Isshin's considerable reiatsu _inwards_ , rather than using it to create more external effects. It acts as a really powerful self-buff, which seems also to fit with Isshin's freakish (even by canon standards) physical strength (see: finger-flicking Aizen through at least two successive buildings). The bankai takes the trait up to eleven by enhancing all of Isshin's physical capacities and making him much more resistant to damage. It lacks any new techniques, but makes most of the physical ones he already uses much more dangerous.

 _Jigoku no Ken_ – 地獄の堅 – "Hell's Armor," basically. It's a technique that Kisuke can use to blend his reiatsu with residual tainted energy from hell, and then solidify that into armor. It's something of a unique technique—not really a kidō as such, certainly not a zanpakutō technique or a Fullbring. The coat itself is very protective, but the more important property of engaging the technique is that it changes the composition of Kisuke's reiatsu to include Hell energy, which if you've read _The Uncertainty Principle_ you know has some pretty interesting properties. One of them is that it doesn't fully interact with kidō the way most energy does—hence why shinigami cannot break chains made of Hell-tainted energy.

 _Jinbaori_ – 陣羽織 – Roughly "Battle array feather weave." It's an outer coat traditionally worn with samurai armor. Samurai would display _mon_ , their house crests, on the jinbaori, usually prominently on the back between the shoulderblades and then sometimes on the lapels on the front. Of course, your house had to be fancy enough to _have_ a mon, hence Kisuke's reference here to not being of a sufficiently-distinguished pedigree himself. The mon on the _Jigoku no Ken_ are representative of Amari, and by extension Hell itself.

 _Zangerin_ – 斬華輪 – "Cutting Flower Ring." Hadō #78. The practitioner generates a large amount of energy from their zanpakutō before blasting it outward with enough power to level a building.

 _Jigokujō_ – 地獄錠 – "Hell Shackles." This kidō made its initial appearance in the last chapter of _The Uncertainty Principle_ , for those of you who read that one. A new bakudō seal Urahara and Amari invented for the purposes of sealing Shuren, since killing him would just result in his eventual reappearance. The spell in its initial form is a sphere of red light, which is then extended and shot as twin bolts into the _Saketsu_ (鎖結) "binding chain," and _Hakusui_ (魄睡) "soul sleep," the important points of spiritual power in any being. Rather than simply destroying them (something which typically robs the soul of its spiritual powers in its current incarnation), this kidō actually uses the reiryoku generated by them to continually reinforce itself: the harder the subject of the seal struggles to use its power to overcome it, the stronger the seal becomes. Which makes it basically perfect for use against Aizen, who has enough reiatsu to vaporize people. Kisuke gave it the number Bakudō #100, to indicate both its relative power requirement and its standing outside the kidō canon (which only goes from 1-99).

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*collapses*

I do apologize that this chapter took so long; I hope its length and content go some way towards making up for that. To be honest, I struggled a lot with writing it—not because I didn't know what I wanted to do, but because getting there was at times a bit of a slog for me. I'm pretty much wiped on fight scenes for a while, I think. Plus it's a bad time in the semester, and a crazy time in the world for various reasons, and so on. Much as I sometimes wish I existed in a vacuum, free of worldly concern, I sadly do not.

In any case, that finishes _Catastrophe Theory_. It does not, of course, finish the _Chaos Theory_ AU. I will probably not be able to write much for the next month or month and a half, just because the end of term is here and I have essays to do, but you can rest assured that I have no intentions of abandoning the series. There's a lot of work still to do on it, and a lot of improving I need to be trying for as a writer.

At times like these, when pretty much everyone is upset for one reason or another, I think it can be prudent to occasionally take a break and remind myself of things I'm grateful for and things that are going right. So, please know that I'm grateful to you, reader, for indulging me in this little lark of mine, and that whoever or wherever you are, you have my honest appreciation and my thanks.

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Reviews very much appreciated.


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